Coincidence time resolution investigation of BaF2-based H6610 detectors for a digital positron annihilation lifetime spectrometer

BaF2-based detectors have been used in many fields requiring fast timing, especially in positron annihilation lifetime (PAL) spectroscopy. The performance of a PAL spectrometer is closely correlated with the time response of BaF2-based detectors. Therefore, it is important to select scintillation detectors with excellent time resolution. In this work, the coincidence time resolution of BaF2-based H6610 detectors was investigated using a digital oscilloscope. The time response of detectors has been optimized by tuning the supply voltages, the sampling rate of the oscilloscope, and digital fraction constants, achieving a conicidence time resolution of about 162 ps for the 0.511 MeV annihilation gamma-ray pairs and 108 ps for the Co-60 cascade gamma-rays, respectively. Furthermore, a digital PAL spectrometer composed of two BaF2-based H6610 detectors and an oscilloscope was developed with a time resolution of around 130 ps, much better than most digital PAL spectrometers.