Decay Times of Commercial Organic Scintillators

Response curves showing both short and long decay components are presented for fifteen commercially-available scintillators. Scintillator time-response functions for detection of 1.114-Mev gamma radiation (Zn-65) were measured over a range of three decades by employing a delayed coincidence technique. The apparatus, which was described in a previous paper, measures time intervals between the start of a gamma-induced scintillation event and the detection of a single visible photon. The region of the decay curve between 70 percent and 7 percent of the peak value is found to be very nearly exponential for most scintillators. The decay time for this region was determined for each scintillator to an accuracy of ±0.1 nanosecond.