482 research outputs found

    Observation of electron-antineutrino disappearance at Daya Bay

    Full text link
    The Daya Bay Reactor Neutrino Experiment has measured a non-zero value for the neutrino mixing angle θ13\theta_{13} with a significance of 5.2 standard deviations. Antineutrinos from six 2.9 GWth_{\rm th} reactors were detected in six antineutrino detectors deployed in two near (flux-weighted baseline 470 m and 576 m) and one far (1648 m) underground experimental halls. With a 43,000 ton-GW_{\rm th}-day livetime exposure in 55 days, 10416 (80376) electron antineutrino candidates were detected at the far hall (near halls). The ratio of the observed to expected number of antineutrinos at the far hall is R=0.940±0.011(stat)±0.004(syst)R=0.940\pm 0.011({\rm stat}) \pm 0.004({\rm syst}). A rate-only analysis finds sin22θ13=0.092±0.016(stat)±0.005(syst)\sin^22\theta_{13}=0.092\pm 0.016({\rm stat})\pm0.005({\rm syst}) in a three-neutrino framework.Comment: 5 figures. Version to appear in Phys. Rev. Let

    A side-by-side comparison of Daya Bay antineutrino detectors

    Get PDF
    The Daya Bay Reactor Neutrino Experiment is designed to determine precisely the neutrino mixing angle θ13\theta_{13} with a sensitivity better than 0.01 in the parameter sin22θ13^22\theta_{13} at the 90% confidence level. To achieve this goal, the collaboration will build eight functionally identical antineutrino detectors. The first two detectors have been constructed, installed and commissioned in Experimental Hall 1, with steady data-taking beginning September 23, 2011. A comparison of the data collected over the subsequent three months indicates that the detectors are functionally identical, and that detector-related systematic uncertainties exceed requirements.Comment: 24 pages, 36 figure

    Measurement of Bose-Einstein Correlations in e+e- -> W+W- at root(s)=189GeV

    Full text link
    We investigate Bose-Einstein correlations (BEC) in W-pair production at root(s)=189GeV using the L3 detector at LEP. We observe BEC between particles from a single W decay in good agreement with those from a light-quark Z decay sample. We investigate their possible existence between particles coming from different W's. No evidence for such inter-W BEC is found

    Composition change-driven texturing and doping in solution-processed SnSe thermoelectric thin films

    Get PDF
    The discovery of SnSe single crystals with record high thermoelectric efficiency along the b-axis has led to the search for ways to synthesize polycrystalline SnSe with similar efficiencies. However, due to weak texturing and difficulties in doping, such high thermoelectric efficiencies have not been realized in polycrystals or thin films. Here, we show that highly textured and hole doped SnSe thin films with thermoelectric power factors at the single crystal level can be prepared by solution process. Purification step in the synthetic process produced a SnSe-based chalcogenidometallate precursor, which decomposes to form the SnSe2 phase. We show that the strong textures of the thin films in the b???c plane originate from the transition of two dimensional SnSe2 to SnSe. This composition change-driven transition offers wide control over composition and doping of the thin films. Our optimum SnSe thin films exhibit a thermoelectric power factor of 4.27 ??W cm???1 K???2

    Improved Measurement of Electron Antineutrino Disappearance at Daya Bay

    Full text link
    We report an improved measurement of the neutrino mixing angle θ13\theta_{13} from the Daya Bay Reactor Neutrino Experiment. We exclude a zero value for sin22θ13\sin^22\theta_{13} with a significance of 7.7 standard deviations. Electron antineutrinos from six reactors of 2.9 GWth_{\rm th} were detected in six antineutrino detectors deployed in two near (flux-weighted baselines of 470 m and 576 m) and one far (1648 m) underground experimental halls. Using 139 days of data, 28909 (205308) electron antineutrino candidates were detected at the far hall (near halls). The ratio of the observed to the expected number of antineutrinos assuming no oscillations at the far hall is 0.944±0.007(stat.)±0.003(syst.)0.944\pm 0.007({\rm stat.}) \pm 0.003({\rm syst.}). An analysis of the relative rates in six detectors finds sin22θ13=0.089±0.010(stat.)±0.005(syst.)\sin^22\theta_{13}=0.089\pm 0.010({\rm stat.})\pm0.005({\rm syst.}) in a three-neutrino framework.Comment: 21 pages, 24 figures. Submitted to and accepted by Chinese Physics C. Two typos were corrected. Description improve

    The muon system of the Daya Bay Reactor antineutrino experiment

    Get PDF
    postprin
    corecore