Performance of four digital algorithms for $\gamma$-$\gamma$ timing with LaBr$_3$(Ce) scintillators

G. Simpson (1) , S. Curtoni (1) , D. Dauvergne (1) , M.-L. Gallin-Martel (1) , S. Marcatilli (1) , G. Thiamova (1)

1 LPSC - Laboratoire de Physique Subatomique et de Cosmologie

Time resolution measurements were performed using four digital timing algorithms and a pair of truncated-cone shaped, 38-mm diameter LaBr(Ce) fast-timing scintillator detectors. The best resolution [FWHM=143(3) ps] was found for transitions from a 60Co source when fitting the rising part of sampled waveforms with a cubic polynomial and applying a leading-edge threshold. An average-pulse autocovariance function performed slightly worse [155(3) ps], but was found to be better than digital constant-fraction [178(4) ps] and leading-edge [177(4) ps] algorithms. Use of a 152Eu source allowed the performance of the four algorithms to be tested across a range of -ray energies with the LaBr(Ce) detectors. Here the autocovariance algorithm performed best. Changing the sampling speed showed minimal degradation in the time resolution at 20 GS/s, though at 4 GS/s the resolutions were 30–60% worse. These results show that at sampling speeds of 20 or 40 GS/s the time resolutions obtained are close to those reported for analogue pulse-processing electronics. Compared to other works, using slower sampling speeds but higher vertical resolution, slightly worse performance was obtained.

Mots clés: Fast timing; Digital timing algorithms; LaBr3(Ce); Time resolution

Domaines: Instrumentations et Détecteurs [physics.ins-det]; Physique Médicale [physics.med-ph]

G. Simpson, S. Curtoni, D. Dauvergne, M.-L. Gallin-Martel, S. Marcatilli, et al.. Performance of four digital algorithms for $\gamma$-$\gamma$ timing with LaBr$_3$(Ce) scintillators. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2019, 40, pp.50-55. ⟨10.1016/j.nima.2019.05.015⟩. ⟨hal-02134630⟩