Speaker
Description
The Jiangmen Underground Neutrino Observatory (JUNO) is a multi-purpose experiment located in southern China, whose primary goal is to determine the neutrino mass ordering and perform precision measurements of the neutrino oscillation parameters. The experiment's central detector is a 35.4 m diameter acrylic sphere filled with 20-kt liquid scintillator (LS). The LS is composed of LAB solvent doped with 2.5 g/L PPO, 3 mg/L bis-MSB, and 50 mg/kg BHT. It is required to have a high light yield, long attenuation length and an ultra low radioactive background. To achieve these specifications, in addition to using specially manufactured high purity raw materials, an on-site LS production line was designed and constructed to purify the LS. The purification process consists of alumina filtration, distillation, mixing, water extraction, and gas stripping. An ultrapure water plant and a high pure nitrogen plant were also built for supporting. At a flow rate of 7 m3/h, 20-kt LS were produced and filled into the JUNO central detector from February to August in 2025. The produced LS achieved the average attenuation length of greater than 20 meters and U/Th contamination levels below 10⁻¹⁶ g/g.