Measurement of photon angles for highly resolved TOF detectors

Particle identifi cation by means of the Time-of-Flight (TOF) technique is widely used in modern spectrometers. Stringent requirements on high resolving power (time resolutions σ < 200 ps) and small scintillator thicknesses (d < 0.5%X0) push the technique close to its limits. One intrinsic limit on the time resolution of low mass scintillation counters comes as a consequence of the statistical processes involved in the generation of the signal. In general, the voltage pulse, VPMT, can be expressed as a linear superposition of Npe single photoelectron pulses, vi, arriving at individual times due to time uncertainties in the energy transfer to the optical scintillator levels, tdep, the decay time of the light emitting states, temit, the propagation time, tpro, and the photomultiplier transit time, tTT: