Quenching of undesired fluorescence in a liquid scintillator particle detector

The efficiency of quenching the fluorescence light in pseudocumene (PC) by the addition of pyridyl and phthalate derivatives (quenchers) has been stud ied both by ultraviolet excitation of PC and by using ionizing particles. T he results show that a controlled reduction of the PC fluorescence is easil y achieved by the addition of quencher in concentrations of a few grams per litre. The scintillation light can be quenched to a level where the Cheren kov light remains the only detectable signal when ionizing particles deposi t energy in the solvent. While these data are of particular interest for th e design of the Borexino buffer, more general applications of these results are envisaged and discussed. (C) 1999 Elsevier Science B.V. All rights res erved.