Measurement of neutrino mixing angle Θ13 in the Daya Bay Reactor Neutrino Experiment

neutrino;Mixing;angle;theta13;daya bay;reactor

Ngai, Wah Kai

关键词: neutrino;    Mixing;    angle;    theta13;    daya bay;    reactor;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/34258/Ngai_WahKai.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Neutrino oscillations have been observed in experiments measuring solar, atmospheric, accelerator and reactor neutrinos. The phenomenon can be described by three mixing angles and three phases. The values of two mixing angles $\theta_{12}$ and $\theta_{23}$ have been pinned down while the value of $\theta_{13}$ was poorly known. The Daya Bay Reactor Antineutrino Experiment was designed to measure $\sin^{2}2\theta_{13}$ with a sensitivity of 0.01 or better by detecting antineutrinos from nuclear reactors with multiple identically designed detectors at different baselines. Antineutrinos were identified by inverse beta decay $\bar{\nu}_{e} + p \rightarrow e^{+} + n$ in 20~tons of Gadolinium-doped liquid scintillator which served as both target and detector. A search for $\bar{\nu}_{e}$ deficits, a process which would manifest a nonzero value of the $\theta_{13}$ mixing angle,was performed. Between December 2011 and Feb 2012, 55 days of data were collected. During this time,80376 and 10416 electron antineutrino candidates were detected with 1545 and 515 expected background events at the near sites and the far site respectively. A rate-only analysissupports neutrino flavor oscillation with $\sin^{2}2\theta_{13} = 0.0936\pm0.0172$ ina 2-neutrino mixing framework.