Nuclear reactor antineutrino has played a special role in neutrino physics starting from the discovery of antineutrino at the Savannah River Plant by Reins and Cowan. After the discovery of neutrino oscillation in the atmospheric neutrino data by Super-K in 1998, neutrino physicists had soon successfully measured two mixing angles, θ12 and θ23, using atmospheric, accelerator and reactor neutrino sources within ~4 years. However, it took almost 10 years to observe the oscillation effect of the last mixing angle θ13. The Daya Bay Reactor Neutrino Experiment was one of the current generation short-baseline neutrino experiments which have measured the θ13 value successfully. In 1st part of this talk, we will present the design and the operation of the Daya Bay experiment, the latest neutrino oscillation results, reactor neutrino flux measurements and new physics searches which had been initiated after the measurements of θ13 and Δm2ee measurements.
Thanks to the unexpected large value of θ13 discovered by the short-baseline reactor neutrino experiments and further confirmed in the long-baseline oscillation experiments, it is now plausible to resolve neutrino mass hierarchy by observing the interplay effect in the reactor neutrino flux survival spectrum between oscillations driven by Δm232 and Δm221 at a medium-baseline distance (~60km). Seizing the historical opportunity, Jiangmen Underground Neutrino Observatory (JUNO) was proposed and has been fully funded in China to measure the neutrino mass hierarchy utilizing two powerful nuclear power plants ~53km away. The JUNO detector is a 20-kiloton liquid scintillator (LS) detector that will be installed in an underground lab with a 700m rock overburden. Besides its unprecedented target mass for a LS detector, two other key elements essential for the mass hierarchy measurement are the unprecedented energy resolution ~3%/√E and its high precision energy scale calibration <1%. Such performance naturally provides JUNO the ability of measuring Δm232 to sub-percent precision. Furthermore, due to its optimized baseline for the solar mass-squared splitting, JUNO is also capable of measuring the solar neutrino mixing parameters θ12 and Δm221 to sub-percent precision. The experiment is also an ideal place observing supernova neutrinos, studying the atmospheric neutrinos, solar neutrinos, geo-neutrinos, and other physics. In the 2nd part of this talk, we will present the design of the JUNO experiment and its detector system, its physics potential, and the current R&D activities to fulfill its designed physics goals.