A Comparison of Constant Fraction and Leading Edge Timing with NaI(Tl) Scintillators

The technique of constant fraction of pulse height is shown to be useful for timing with NaI(Tl) scintillators. A comparison of the results of constant fraction timing with leading edge timing indicates that the two techniques are equivalent for small dynamic ranges. For large dynamic ranges constant fraction timing is shown to be a significant improvement over leading edge timing. Also, constant fraction timing over narrow dynamic ranges represents an improvement of 13.7 over the slow crossover timing with NaI(Tl) as reported by Bell. Multiple time sampling is used to investigate how much time information is contained in a NaI(Tl) scintillator pulse. Since an additional time sample represents an improvement of only 11 percent over a single constant fraction measurement, it is concluded that a system more sophisticated than constant fraction will not significantly improve the time resolution.