Search

The Cryogenic Dark Matter Search (CDMS) uses low-temperature Ge and Si detectors to search for Weakly Interacting Massive Particles (WIMPs) via their elastic-scattering interaction with atomic nuclei while discriminating against interactions of background particles. CDMS data from 1998 and 1999 with a relaxed fiducial-volume cut (resulting in 15.8 kg-days exposure on Ge) are consistent with an earlier analysis with a more restrictive fiducial-volume cut. Twenty-three WIMP candidate events are observed, but these events are consistent with a background from neutrons. Resulting limits on the spin-independent WIMP-nucleon elastic-scattering cross-section are lower than those of any other experiment for WIMPs with masses between 10–70 GeV c −2 . Under the assumptions of standard WIMP interactions and a standard halo, the results are incompatible with the annual-modulation signal of DAMA at 99.99% CL in the asymptotic limit.

The CDMS experiment utilizes Ge and Si detectors operating at 20 mK to search for the Dark Matter of the Universe hypothesized to exist in the form of weakly interacting massive particles (WIMPs). In early 2000, CDMS set the most competitive exclusion limit for scalar-interaction WIMPs in the Stanford Underground Facility (SUF). A new search (CDMS II) is now commencing with several improvements: a deep-site facility in the Soudan mine, Minnesota; and the detector technology has been further improved to aid in the rejection of surface-electron (β) events. A new generation of detectors, sensitive to the initial athermal phonon flux from a particle event, have been in operation for the past year at Stanford's shallow site and are ready for installation at the deep site.