  Liquid scintillator (LS) will be adopted as the detector material in JUNO
(Jiangmen Underground Neutrino Observatory). The energy resolution requirement
of JUNO is 3%, which has never previously been reached. To achieve this energy
resolution, the light yield of liquid scintillator is an important factor. PPO
(the fluor) and bis-MSB (the wavelength shifter) are the two main materials
dissolved in LAB. To study the influence of these two materials on the
transmission of scintillation photons in LS, 25 and 12 cm-long quartz vessels
were used in a light yield experiment. LS samples with different concentration
of PPO and bis-MSB were tested. At these lengths, the light yield growth is not
obvious when the concentration of PPO is higher than 4 g/L. The influence from
bis-MSB becomes insignificant when its concentration is higher than 8 mg/L.
This result could provide some useful suggestions for the JUNO LS.
