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Of dark matter and hope

16 Apr 2013, 21:06 UTC
Of dark matter and hope
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Perhaps hope lies deep underground. Specifically, hope of detecting dark matter: the stuff making up 80 percent of the total mass of the Universe.
The headframe of the Soudan Iron Mine, which still operates the lift cage descending a half-mile below ground, where the CDMS experiment is located. I visited Soudan last May. [Credit: moi]Yesterday, researchers working with the Cryogenic Dark Matter Search (CDMS) announced a possible detection of three dark matter particles. They’re right to be cautious: several marginal observations of dark matter particles have been announced over the years, only to be squashed by later examination. The recent Alpha Magnetic Spectrometer (AMS-02) results were heavily hyped, and while they might have dark matter hiding in them, the data are far too ambiguous to say anything either way yet.
The new announcement is a different beast. Rather than looking for elevated positron levels from dark matter annihilation as AMS-02 does, CDMS is a set of solid geranium germanium crystals, cooled by liquid helium to 40 millikelvins—0.04° C above absolute zero. If a dark matter particle known as a WIMP (weakly interacting massive particle) hits a nucleus inside the crystal, it will set up a small vibration: a quantum sound ...

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