Optical purification pilot plant for JUNO liquid scintillator

The Jiangmen Underground Neutrino Observatory (JUNO) is a large-scale neutrino detector with 20 kton high transparency liquid scintillator (LS). To increase the attenuation length of LS, alumina absorption columns are used to purify the optical impurities in Linear Alkyl Benzene (LAB), the raw material of LS. Prototypes of absorption columns were constructed to test absorption material and parameters that could affect the purification efficiency including column height-diameter ratio and flow rate. Meanwhile, the pilot plant of alumina purification system was built in the Daya Bay Neutrino Laboratory to test the design and operation process, provide parameter reference for the design of JUNO purification system. The alumina purification pilot plant can increase the attenuation length of LAB from 20 m to more than 24 m without introducing radioactive background at 10−15 g/g level. The pilot plant of alumina purification system can meet the JUNO requirements in LS optical purification.