The EDELWEISS experiment has improved its sensitivity for the direct search for WIMP dark matter. In the recoil energy range relevant for WIMP masses below 10 TeV/c 2 , no nuclear recoils were observed in the fiducial volume of a heat-and-ionization cryogenic Ge detector operated in the lowbackground environment of the Laboratoire Souterrain de Modane in the Fréjus Tunnel, during an effective exposure of 7.4 kg·d. This result is combined with the previous EDELWEISS data to derive a limit on the crosssection for spin-independent interaction of WIMPs and nucleons as a function of WIMP mass, using standard nuclear physics and astrophysical assumptions. This limit excludes at more than 99.8%CL a WIMP candidate with a mass of 44 GeV/c 2 and a cross-section of 5.4×10 −6 pb, as reported by the DAMA collaboration. A first sample of supersymmetric models are also excluded at 90%CL.

21 pages, 5 figuresThe EDELWEISS-II collaboration has completed a direct search for WIMP dark matter with an array of ten 400-g cryogenic germanium detectors in operation at the Laboratoire Souterrain de Modane. 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 kg.d has been achieved, mostly coming from fourteen months of continuous operation. Five nuclear recoil candidates are observed above 20 keV, while the estimated background is less than 3.0 events. The result is interpreted in terms of limits on the cross-section of spin-independent interactions of WIMPs and nucleons. A cross-section of 4.4x10^-8 pb is excluded at 90%CL for a WIMP mass of 85 GeV. New constraints are also set on models where the WIMP-nucleon scattering is inelastic