  A new Digital Pulse Processing (DPP) system, based on domino ring sampler
version 4 (DRS4), with good time resolution for the LaBr3 detectors has been
developed and different digital timing analysis methods for processing the
detector raw signals are reported. The system, composed of an eight channels
DRS4 chip, was used as the readout electronic and acquisition system to process
the outputs signals from XP20D0 Photomultiplier Tubes (PMTs). The PMTs were
coupled with LaBr3 scintillator and placed on opposite side of the radioactive
positron 22Na source for 511keV gama-ray test. By analyzing the raw data
acquired by the system, the best coincidence timing resolution is about 194.7ps
(FWHM), obtained by the digital constant fraction discrimination (dCFD) method
and better than the other digital methods and analysis method based on the
conventional analog systems. The results indicate that it is a promising
approach to better localize the positron annihilation in the positron emission
tomography (PET) with time of flight (TOF) and they are also suitable for the
scintillation timing measurement, such as in TOF-DeltaE and TOF-E systems for
particle identification, with picosecond accuracy timing measurement.
Furthermore, this system is more simple and convenient in comparison with other
systems.
