  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 C-14/C-12 = 9.1 * 10^{-18}$ has been measured in the
scintillator. Initial trace impurities, e.g. U-238 at 3.2 * 10^{-14} g/g could
be purified to levels below 10^{-17} g/g by silica gel solid column
purification.
