Lower bounds on scintillation detector timing performance

Abstract

Fundamental method-independent limits on the timing performance of scintillation detectors are useful for identifying regimes in which either present timing methods are nearly optimal or where a considerable performance gain might be realized using better pulse processing techniques. Several types of lower bounds on mean-squared timing error (MSE) performance have been developed and applied to scintillation detectors. The simple Cramer-Rao (CR) bound can be useful in determining the limiting MSE for scintillators having a relatively high rate of photon production such as BaF2 and NaI(Tl); however, it tends to overestimate the achievable performance for scintillators with lower rates such as BGO. For this reason, alternative bounds have been developed using rate-distortion theory [1,2] or by assuming that the conversion of energy to scintillation light must pass through excited states which have exponential lifetime densities [3]. The bounds are functions of the mean scintillation pulse shape, the scintillation intensity, and photodetector characteristics; they are simple to evaluate and can be used to conveniently assess the limiting timing performance of scintillation detectors.