Study of attenuation length of linear alkyl benzene as LS solvent

Linear alkyl benzene (LAB) is an attractive solvent for large scale liquid scintillator detectors due to its low toxicity, high flash point, and good compatibility with acrylic. Very good optical purity is required to be used in large scale detectors. We studied several LAB samples collected from two companies by measuring the light attenuation length, UV-Vis absorption spectrum, and some other properties. Some of them have not good optical transparency. Compositions of these samples were then analyzed by GC-MS and two dimensional GCxGC/MS. Some impurities, such as nitrobenzene derivatives and thiocarbonyl salts, were detected in the failed samples. These impurities' light-absorption properties in the wavelength region 350-550 nm were theoretically investigated by PCM-TDDFT. Calculation results show that two of these impurity compounds can greatly decrease the light transmission of LAB in 350-550 nm. We also tried several purification procedures and found some of them can improve LAB's optical transparency effectively.