We report on the study of a new liquid scintillator target for neutrino interactions in the framework of the research and development program of the Borexino solar neutrino experiment .
The scintillator consists of 1,2–dimethyl–4– ( 1–phenylethyl ) –benzene ( phenyl–o–xylylethane , PXE ) as solvent and 1,4-diphenylbenzene ( para-Terphenyl , p-Tp ) as primary and 1,4-bis ( 2-methylstyryl ) benzene ( bis-MSB ) as secondary solute .
The density close to that of water and the high flash point makes it an attractive option for large scintillation detectors in general .
The study focused on optical properties , radioactive trace impurities and novel purification techniques of the scintillator .
Attenuation lengths of the scintillator mixture of 12 m at 430 nm were achieved after purification with an alumina column .
A radio carbon isotopic ratio of ^ { 14 } C / ^ { 12 } C = 9.1 \times 10 ^ { -18 } has been measured in the scintillator .
Initial trace impurities , e.g . ^ { 238 } U at 3.2 \times 10 ^ { -14 } g/g could be purified to levels below 1 \times 10 ^ { -17 } g/g by silica gel solid column purification .