Enhanced time response of 1-in. LaBr3(Ce) crystals by leading edge and constant fraction techniques

TL;DR

This study improves the time resolution of 1-inch LaBr3(Ce) detectors using leading edge and constant fraction techniques, achieving sub-100 ps resolution at gamma-ray energies, influenced by Ce doping and crystal quality.

Contribution

It demonstrates enhanced timing performance of LaBr3(Ce) detectors through optimized CFD parameters and specific doping levels, surpassing previous time resolution records.

Findings

Achieved sub-100 ps time resolution with optimized techniques.

Timing performance depends on Ce doping and crystal homogeneity.

Improved detector timing at gamma-ray energies.

Abstract

We have characterized in depth the time response of three detectors equipped with cylindrical LaBr$_{3}$ (Ce) crystals with dimensions of 1-in. in height and 1-in. in diameter, and having nominal Ce doping concentration of 5%, 8% and 10%. Measurements were performed at $^{60}$Co and $^{22}$Na {\gamma}-ray energies against a fast BaF$_{2}$ reference detector. The time resolution was optimized by the choice of the photomultiplier bias voltage and the fine tuning of the parameters of the constant fraction discriminator, namely the zero-crossing and the external delay. We report here on the optimal time resolution of the three crystals. It is observed that timing properties are influenced by the amount of Ce doping and the crystal homogeneity. For the crystal with 8% of Ce doping the use of the ORTEC 935 CFD at very shorts delays in addition to the Hamamatsu R9779 PMT has made it possible to improve the LaBr$_{3}$(Ce) time resolution from the best literature value at 60Co photon energies to below 100 ps.