First Results from the Cryogenic Dark Matter Search at Soudan

We report the first results from a search for weakly interacting massive particles (WIMPs) in the Cryogenic Dark Matter Search (CDMS) experiment at the Soudan Underground Laboratory. Four Ge and two Si detectors were operated for 52.6 live days, providing 19.4 kg-d of Ge net exposure after cuts for recoil energies between 10-100 keV. A blind analysis was performed using only calibration data to define the energy threshold and selection criteria for nuclear-recoil candidates. Using a standard dark matter halo distribution and nuclear-physics WIMP model, these data set the world's lowest exclusion limits on the coherent WIMP-nucleon scalar cross-section for all WIMP masses above 13 GeV/c², ruling out a significant range of neutralino supersymmetric models. The best sensitivity at the minimum of the limit curve corresponds to a 90% C.L. cross-section exclusion of 4 × 10^-43 cm² at a WIMP mass of 60 GeV/c².