Measurement of timing properties of the fluorescence fast component from plastic scintillators

Abstract The measurement is described of timing properties of the fluorescence fast component for five types of polystyrene scintillators. The description is presented of a spectrometer with three counters in a telescope which operates using the single photon method. The measurements have been performed using XP1020 photomultipliers. Samples of 1×50×50 mm 3 scintillators were exposed to electrons of a 90 Sr β -source with a maximum energy of 2.26 MeV. Cherenkov light was used as a zero-time reference in time-distribution measurements. The rise time constant of the light pulse of a scintillator with PBD (about 60 ps) and the decay time of this scintillator (1.4 ns) have been obtained experimentally. In this case the rise time constant is commensurable with the time spread of light collection according to the experimental geometry. The rise time constant of the light pulse for a scintillator with p-terphenyl + POPOP is about 800 ps. The time of population of the intermediate level is determined by this value. According to our data, its lifetime is equal to 2.3 ns.