Speaker
Dr
Vitaly Kudryavtsev
(University of Sheffield)
Description
The EDELWEISS-II collaboration has carried out a direct search for dark matter
WIMPs (Weakly Interacting Massive Particles) with an array of ten 400 g germanium
detectors operated at cryogenic temperatures of about 10 mK in the Modane
Underground Laboratory (France). The combined use of thermal phonon sensors and
charge collection electrodes with an interleaved geometry enables the efficient
rejection of gamma-induced radioactivity as well as near-surface interactions. A total
effective exposure of 384 kgd has been obtained and five events have been observed
above 20 keV in the region where WIMP interactions are expected with the
estimated background being less than 3.0 events. The result has been interpreted in
terms of limits on the cross-section of WIMP interactions with matter. Cross-sections
above 4.4×10-8 pb are excluded at 90%CL for a WIMP mass of 85 GeV. This
significant progress in detector sensitivity has been achieved thanks to the
development of a new technique of background rejection using inter-digit electrodes.
The EDELWEISS-II Collaboration is working on improving the background rejection
techniques to be able to reach an order of magnitude better sensitivity in a couple of
years.
Primary author
Dr
Vitaly Kudryavtsev
(University of Sheffield)
