Dark Detections

StarDate: August 7, 2013

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Three little blips. In months of operation, an array of silicon detectors buried in a mile—deep mine in Minnesota detected three little blips of energy. But it’s possible that those blips could represent the first detection of dark matter — particles that make up most of the matter in the universe.

Dark matter produces no detectable energy, and it almost never interacts with normal matter. It reveals its presence, though, by pulling on the visible matter around it. It probably consists of subatomic particles, which may take the form of WIMPs — Weakly Interacting Massive Particles.

Physicists look for the extremely rare interactions between WIMPs and normal matter by placing detectors far underground. That screens out most of the other particles that could trigger the detectors. Special shielding screens out more particles. So there’s a good chance that any reaction in the detectors is caused by dark matter.

A few months ago, an experiment called SuperCDMS reported the detection of three possible WIMPs in its silicon detectors. The detections need confirmation, though — they could be false alarms.

About a year ago, an experiment in Italy reported no evidence of WIMPs despite many months of looking. That experiment uses liquid xenon as its target medium. And another experiment just started operating in Ontario. Its detectors use water plus a chemical found in fire extinguishers — all part of the effort to detect some common but “wimpy” particles.

 

Script by Damond Benningfield, Copyright 2013

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