Measurement of subnanosecond scintillation decay times by time-correlated single photon counting☆

Abstract A time-correlated single photon counting system for measuring scintillation decay times is described in which the system time response function has a FWHM less than 220 ps. This is a two-scintillator system in which a time-to-amplitude converter (TAC) is started by gamma-induced flashes from a bright 500-ps FWHM scintillator closely coupled to a 14-stage photomultiplier. The TAC is stopped by single-photon pulses from an amplified high-gain microchannel-plate photomultiplier viewing the sample. A 60 Co source is sandwiched between the start scintillator and the sample to be measured. The time correlation depends on the coincident excitation of both scintillators by the two γ rays from each nuclear disintegration.