Observations of neutral-current ν interactions on deuterium in the Sudbury Neutrino Observatory are reported. Using the neutral current, elastic scattering, and charged current reactions and assuming the standard 8 B shape, the

The Sudbury Neutrino Observatory (SNO) has measured day and night solar neutrino energy spectra and rates. For charged current events, assuming an undistorted 8B spectrum, the night minus day rate is 14.0%+/-6.3%(+1.5%)(-1.4%) of the average rate. If the total flux of active neutrinos is additionally constrained to have no asymmetry, the nu(e) asymmetry is found to be 7.0%+/-4.9%(+1.3%)(-1.2%). A global solar neutrino analysis in terms of matter-enhanced oscillations of two active flavors strongly favors the large mixing angle solution.

Solar neutrinos from (8)B decay have been detected at the Sudbury Neutrino Observatory via the charged current (CC) reaction on deuterium and the elastic scattering (ES) of electrons. The flux of nu(e)'s is measured by the CC reaction rate to be straight phi(CC)(nu(e)) = 1.75 +/- 0.07(stat)(+0.12)(-0.11)(syst) +/- 0.05(theor) x 10(6) cm(-2) s(-1). Comparison of straight phi(CC)(nu(e)) to the Super-Kamiokande Collaboration's precision value of the flux inferred from the ES reaction yields a 3.3 sigma difference, assuming the systematic uncertainties are normally distributed, providing evidence of an active non- nu(e) component in the solar flux. The total flux of active 8B neutrinos is determined to be 5.44+/-0.99 x 10(6) cm(-2) s(-1).

The Cryogenic Dark Matter Search (CDMS) employs Ge and Si detectors to search for weakly interacting massive particles (WIMPs) via their elastic-scattering interactions with nuclei while discriminating against interactions of background particles. CDMS data, accounting for the neutron background, give limits on the spin-independent WIMP-nucleon elastic-scattering cross section that exclude unexplored parameter space above 10 GeV͞c 2 WIMP mass and, at .75% C.L., the entire 3s allowed region for the WIMP signal reported by the DAMA experiment. Extensive evidence indicates that a large fraction of the matter in the universe is nonluminous, nonbaryonic, and "cold"-nonrelativistic at the time matter began to dominate the energy density of the universe [1][2][3]. Weakly interacting massive particles (WIMPs) are an excellent candidate for nonbaryonic, cold dark matter [2,4]. Minimal supersymmetry provides a natural WIMP candidate in the form of the lightest superpartner, with a typical mass M ϳ 100 GeV͞c 2 [5][6][7][8]. WIMPs are expected to have collapsed into a roughly isothermal, spherical halo within which the visible portion of our galaxy resides. WIMPs scatter off nuclei via the weak interaction, potentially allowing their direct detection [9,10]. The expected spectrum of recoil energies (energy given to the recoiling nucleus during the interaction) is exponential with a characteristic energy of a few to tens of keV [11]. The expected event rate is model dependent, but is generically 1 kg 21 d 21 or lower [10].This Letter reports new exclusion limits on the spinindependent WIMP-nucleon elastic-scattering cross section by the Cryogenic Dark Matter Search (CDMS). The rate of rare WIMP-nucleon interactions is constrained by extended exposure of detectors that discriminate WIMPinduced nuclear recoils from electron recoils caused by interactions of background particles [12,13].The ionization yield Y (the ratio of ionization production to recoil energy in a semiconductor) of a particle interaction differs greatly for nuclear and electron recoils. CDMS detectors measure phonon and electron-hole pair production to determine recoil energy and ionization yield for each event. The data discussed here were obtained with two types of detectors, Berkeley Large Ionization-and Phonon-mediated (BLIP) and Z-sensitive Ionization-and Phonon-mediated (ZIP) detectors [12][13][14][15][16][17][18]. For both types, the drift field for the ionization measurement is supplied by radially segmented electrodes on the faces of the disk-shaped crystals [19]. In BLIP detectors, phonon production is determined from the detector's calorimetric temperature change. In ZIP detectors, athermal phonons are collected to determine phonon production and xy position. Detector performance is discussed in detail elsewhere [14,[16][17][18][19][20].Photons cause most bulk electron recoils, while lowenergy electrons incident on the detector surfaces cause low-Y electron recoils in a thin surface layer ("surface events"). Neutron, photon, and electron sources ar...

The Cryogenic Dark Matter Search (CDMS) employs Ge and Si detectors to search for weakly interacting massive particles (WIMPs) via their elastic-scattering interactions with nuclei while discriminating against interactions of background particles. CDMS data, accounting for the neutron background, give limits on the spin-independent WIMP-nucleon elastic-scattering cross section that exclude unexplored parameter space above 10 GeV͞c 2 WIMP mass and, at .75% C.L., the entire 3s allowed region for the WIMP signal reported by the DAMA experiment. Extensive evidence indicates that a large fraction of the matter in the universe is nonluminous, nonbaryonic, and "cold"-nonrelativistic at the time matter began to dominate the energy density of the universe [1][2][3]. Weakly interacting massive particles (WIMPs) are an excellent candidate for nonbaryonic, cold dark matter [2,4]. Minimal supersymmetry provides a natural WIMP candidate in the form of the lightest superpartner, with a typical mass M ϳ 100 GeV͞c 2 [5][6][7][8]. WIMPs are expected to have collapsed into a roughly isothermal, spherical halo within which the visible portion of our galaxy resides. WIMPs scatter off nuclei via the weak interaction, potentially allowing their direct detection [9,10]. The expected spectrum of recoil energies (energy given to the recoiling nucleus during the interaction) is exponential with a characteristic energy of a few to tens of keV [11]. The expected event rate is model dependent, but is generically 1 kg 21 d 21 or lower [10]. This Letter reports new exclusion limits on the spinindependent WIMP-nucleon elastic-scattering cross section by the Cryogenic Dark Matter Search (CDMS). The rate of rare WIMP-nucleon interactions is constrained by extended exposure of detectors that discriminate WIMPinduced nuclear recoils from electron recoils caused by interactions of background particles [12,13].The ionization yield Y (the ratio of ionization production to recoil energy in a semiconductor) of a particle interaction differs greatly for nuclear and electron recoils. CDMS detectors measure phonon and electron-hole pair production to determine recoil energy and ionization yield for each event. The data discussed here were obtained with two types of detectors, Berkeley Large Ionization-and Phonon-mediated (BLIP) and Z-sensitive Ionization-and Phonon-mediated (ZIP) detectors [12][13][14][15][16][17][18]. For both types, the drift field for the ionization measurement is supplied by radially segmented electrodes on the faces of the disk-shaped crystals [19]. In BLIP detectors, phonon production is determined from the detector's calorimetric temperature change. In ZIP detectors, athermal phonons are collected to determine phonon production and xy position. Detector performance is discussed in detail elsewhere [14,[16][17][18][19][20].Photons cause most bulk electron recoils, while lowenergy electrons incident on the detector surfaces cause low-Y electron recoils in a thin surface layer ("surface events"). Neutron, photon, and electron sources a...