[en] Linear alkyl benzene(LAB) has many advantages of appreciable light yield, relatively long light attenuation length and environment friendly, etc. It is selected as the LS solvent in the Daya Bay Reactor Neutrino Experiment. To make sure that LAB can meet the experimental requirements on light attenuation length in the 350-450 nm wavelength rang, we developed an improved system to measure, in a faster and more accurate way, light attenuation length of the LAB liquid samples. LAB samples before and after purification by filtration with β-Al₂O₃ and silica gel powders were measured, and composition analyses of the LAB samples were performed. In the experiments we found the chemical impurities that reduced the light attenuation length of the LAB product, and based on the findings the producer optimized the production process to reduce the impurity concentration. The LAB product is qualified for its application in the Daya Bay Reactor Neutrino Experiment. (authors)

[en] In the Daya Bay Reactor Neutrino Experiment 960 20-cm-diameter waterproof photomultiplier tubes are used to instrument three water pools as Cherenkov detectors for detecting cosmic-ray muons. Of these 960 photomultiplier tubes, 341 are recycled from the MACRO experiment. A systematic program was undertaken to refurbish them as waterproof assemblies. In the context of passing the water leakage check, a success rate better than 97% was achieved. Details of the design, fabrication, testing, operation, and performance of these waterproofed photomultiplier-tube assemblies are presented