Performance Evaluation of Liquinert-Processed CeBr Crystals Coupled with a Multipixel Photon Counter

Ce-doped scintillators are capable of shortening the time constant as the luminescence is caused by 5d to 4f transition of Ce3+. A scintillator with a short-time constant is suitable for time-of-flight (TOF)-positron emission tomography (PET). In this article, we conducted an evaluation of the energy resolution and coincidence resolving time (CRT) of Liquinert-processed cerium (III) bromide (CeBr3), which possesses a short-time constant and has a high light yield, using multipixel photon counter (MPPC) as a photon detector. The results indicate that an energy resolution of 5.02% (full width at half maximum (FWHM)) can be obtained from a 5-mm × 5-mm × 5-mm-CeBr3 cube coupled with a 6.0-mm × 6.0-mm-pitch MPPC. Furthermore, a CRT of 97.0 ps (FWHM) was achieved using a 3-mm × 3-mm × 1-mm-CeBr3 array coupled with a 3.0-mm × 3.0-mm-pitch through-silicon-via MPPC array, which has been proven effective for TOF-PET and Compton imaging. Moreover, a CRT of 198.7 ps (FWHM) was obtained using a current comparing type time-over-threshold circuit as a front-end readout application. We also determined that the energy resolution is independent of the shaping time but depends on the temperature. In addition, the CRT was found to be dependent on the frequency bandwidth of the signal measuring instrument.