Decay-time of scintillations in CsI (T1) crystal

Summary

Decay times of scintillations excited in a CsI (T1) crystal byα-particles andγ-rays have been studied for the two regions of the emission spectrum, blue and yellow. Voltage pulses from a photo-multiplier tube, viewing the crystal, as seen on a high-speed oscilloscope have been photographed and investigated. There are two decay components, short- and long-lived. In the case of the long-lived component (τ=10µ sec.) there is no significant variation in decay time with the nature of excitant or the type of emission band. In the case of the short-lived component there is no variation with the type of emission band but there is a marked decrease in the decay time forα-particle excitation (τ=0·5µ sec.) compared to that forγ-rays (γ=0·9 µ sec.).