Temperature dependence of spurious pulses in use of plastic scintillation detectors

Pulse-height and time spectra of afterpulses from a scintillation detector with NE102A scintillator sandwiching a Co-60 source were observed at several different temperatures. From time analysis with a slow amplifier followed by a conventional TAC, spurious pulses are grouped into two types; time-dependent afterpulses and random noise. The intensity of afterpulses decreased considerably with increasing temperature, while the intensity of random noise pulses increased abruptly above 50degreesC. Experiments, in which the temperatures of scintillator sheets and of the photomultiplier tube were changed separately, suggested that the time-dependent afterpulses were produced in the scintillator itself, while the random component arose from photomultiplier tube. (C) 2003 Elsevier Ltd. All rights reserved.