Edelweiss: deeper into the darkness Print E-mail

ImageNew results from the Edelweiss experiment have just been reported. After one full year of operation, the new-generation germanium detectors confirmed their spectacular ability to discriminate the background...



An important turning point was reached in 2007 with the development of a new electrode design that enables the efficient rejection of natural radioactivity occurring at the surface of the detectors, which previously mimicked the expected WIMP signal features. These 400 g detectors were tested successfully in 2008, and used for the first time in a WIMP search the following year. Over a 6-month period, 10 of these detectors demonstrated high levels of reliability and robustness, improving the sensitivity to WIMPs by a factor of 15 relative to the previous generation of detectors. The preliminary analysis of an additional six months of data confirms their effectiveness at the WIMP hunt, with a further factor of two increase in sensitivity.
New prototypes with larger mass, improved sensors implantation and readout capabilities have been installed this month. They will have the capability of addressing new forms of backgrounds , with hints having appeared in the recent data, and ultimately yield a factor 10 increase of sensitivity in the coming future.
With these breakthroughs, Edelweiss will be able to join the elite group of the few experiments around the world able to achieve sufficient sensitivity to discover WIMPs as predicted by theoretical models. This community of competing but complementary experiments will be needed to confirm any hints of this major discovery. Interestingly, the coming years may see concur two very different experimental endeavours: the production of WIMPs at the LHC, at CERN, and, deep under the Fréjus mountain, Edelweiss may show that these particles indeed populate our galaxy, the Milky Way.

Submitted by Gilles Gerbier (CEA / IRFU - France)

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