Space: Elusive Dark Matter May Be Hidden on Earth

[bystander]

Elusive Dark Matter May Be Hidden on Earth
Space.com - 2010 Feb 25

Scientists are hot on the tail of one of nature's most elusive substances, the mysterious dark matter that is thought to make up the bulk of the universe. Many scientists think dark matter might even be hiding right under our noses here on Earth.

Dark matter is especially tricky to find because of its dark nature. In fact, scientists don't know what it is. It doesn't emit or reflect any light, so the most powerful telescopes have no hope of spying it directly. It has been thought to exist since the 1970s based on observations of gravity's effects on large-scales, such as among and between galaxies – regular matter can't account for the amount of gravity at work.
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The Cryogenic Dark Matter Search (CDMS) is buried in a mine in Minnesota underneath about 766 yards (700 meters) of rock, plastic, lead, copper and other materials designed to stop everything but dark matter from reaching the experiment — thus cosmic rays and other particles that might be confused for dark matter particles will mostly be eliminated.

Science Daily: Cryogenic Dark Matter Search: 2010 Feb 20
Science DOI: 10.1126/science.1186112 (2010 Feb 11)

[bystander]

A CoGeNT result in the hunt for dark matter
Nature | doi:10.1038/news.2010.97 | 2010 Feb 26

Deep in the Soudan mine in Minnesota, some 700 metres below ground amid the bones of bats, sits the huge Cryogenic Dark Matter Search (CDMSII) experiment, which at its heart contains a rack of supercooled hockey-puck-sized silicon and germanium detectors nestled within Russian-doll layers of shielding.
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Just a stone's throw from the CDMSII experiment, across the subterranean cavern, lies a far smaller box that is thickening the dark-matter plot. The box contains a single germanium hockey puck, similar to those in the CDMSII experiment but operated by the Coherent Germanium Neutrino Technology (CoGeNT) collaboration and tuned to detect incoming particles with much lower masses than the CDMSII. It began collecting data in December 2009, and, after just 56 days, the group is reporting hundreds of particle strikes that cannot be explained other than by invoking dark matter.
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Confirmation of the result — and Collar is careful to say that it is still early days — would radically shift attention to experiments that are sensitive to lower energies. The CoGeNT experiment looks for a type of dark-matter particle called a WIMP, or Weakly Interacting Massive Particle. The new data point to a WIMP with a mass in the range of 7–11 billion electronvolts. Theorists have conjured up hundreds of mathematically consistent models for producing WIMPs of different masses in the early Universe, and the particles detected by CoGeNT fit well in the realm of the theoretically possible.

arXiv.org > astro-ph > arXiv:1002.4703 (2010 Feb 25)