The Daya Bay experiment, a collaboration of scientists from the United States, the Republic of China, and Europe, will measure how anti-neutrinos change from one flavor to another (electron neutrinos into muon or tau neutrinos). Three underground experimental halls are being constructed in a mountain near a nuclear power plant complex that supplies power to Hong Kong and Shenzhen. Each hall will have a water pool with instrumentation to detect and cancel cosmic background radiation from the sun, atmosphere, and surrounding rock. Eight anti-neutrino detectors (large tank with transparent vessels filled with special liquids and instrumentation) will be installed into these pools. The number measured in the two halls nearest to the reactors will be compared to the number of neutrinos measured in the hall about 2km away to determine how many neutrinos are “disappearing” or changing. This measurement will allow the collaboration to determine the last unknown neutrino mixing angle θ₁₃ and make progress towards understanding the predominance of matter in the Universe.

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