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تسجيل مستخدم جديدObservation of electron antineutrino disappearance by the Daya Bay Reactor Neutrino Experiment
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Elizabeth Worcester
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This presentation describes a measurement of the neutrino mixing parameter, sin^2(2theta_13), from the Daya Bay Reactor Neutrino Experiment. Disappearance of electron antineutrinos at a distance of ~2 km from a set of six reactors, where the reactor flux is constrained by near detectors, has been clearly observed. The result, based on the ratio of observed to expected rate of antineutrinos, using 139 days of data taken between December 24, 2011 and May 11, 2012, is sin^2(2theta_13) = 0.089 +/- 0.010(stat.) +/- 0.005(syst.). Improvements in sensitivity from inclusion of additional data, spectral analysis, and improved calibration are expected in the future.
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With the end of Daya Bay experimental operations in December 2020, I review the history, discoveries, measurements and impact of the Daya Bay reactor neutrino experiment in China.
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The Double Chooz experiment has observed 8,249 candidate electron antineutrino events in 227.93 live days with 33.71 GW-ton-years (reactor power x detector mass x livetime) exposure using a 10.3 cubic meter fiducial volume detector located at 1050 m
from the reactor cores of the Chooz nuclear power plant in France. The expectation in case of theta13 = 0 is 8,937 events. The deficit is interpreted as evidence of electron antineutrino disappearance. From a rate plus spectral shape analysis we find sin^2 2{theta}13 = 0.109 pm 0.030(stat) pm 0.025(syst). The data exclude the no-oscillation hypothesis at 99.8% CL (2.9{sigma}).
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We report an improved measurement of the neutrino mixing angle $theta_{13}$ from the Daya Bay Reactor Neutrino Experiment. We exclude a zero value for $sin^22theta_{13}$ with a significance of 7.7 standard deviations. Electron antineutrinos from six
reactors of 2.9 GW$_{rm th}$ 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 $0.944pm 0.007({rm stat.}) pm 0.003({rm syst.})$. An analysis of the relative rates in six detectors finds $sin^22theta_{13}=0.089pm 0.010({rm stat.})pm0.005({rm syst.})$ in a three-neutrino framework.
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