Speaker
Description
The Jiangmen Underground Neutrino Observatory (JUNO) is a multiple-purpose neutrino experiment with a 20-kiloton liquid scintillator detector. Its primary goal is the determination of the neutrino mass ordering by detecting the inverse beta decay events induced by antineutrinos from two nuclear reactor power plants placed at about 53 km distance. The scintillation light will be read by about 18000 photomultipliers, mounted on a stainless steel truss which supports also the acrylic sphere (35 m of diameter) containing the scintillator. Low background is essentially important for the low energy neutrino physics. In order to determine the neutrino mass ordering with reactor antineutrinos, the single triggered readout rate induced by the material radioactivity should be controlled below 10 Hz or so within the detector fiducial volume (R < 17.2 m) with the visible energy greater than 0.7 MeV, which leads to about one accidental coincidence per day in the energy interval of interest for inverse beta decay events. The detection of solar neutrinos, on the other hand, will rely on the elastic scattering process which does not produce coincidence signatures, therefore special background reduction method is needed to achieve high sensitivity in the solar neutrino analysis. In this report, I will show the background requirement and its impact on the study of different physical sources, such as reactor antineutrinos and solar neutrinos. Finally, I will discuss the radioactivity budget and control plans, and highlight some major detector components, including the liquid scintillator, the photomultipliers, the stainless steel truss and the acrylic sphere.
