LSO/photodiode and LSO avalanche photodiode detectors

The performance of Lu_2(1-x)Ce_2x(SiO₄ )O (LSO) detectors was assessed under laboratory conditions. The PMT (photomultiplier tube) and the APD (avalanche photodiode) gave the same energy resolution when used with LSO, although the APD displayed a thermal noise threshold of 30 keV compared to <5 keV for the PMT. The PD resulted in a power energy resolution of 14% and also a considerably higher noise threshold of 140 keV. One notable advantage of LSO scintillators over CsI(Tl) and CdWO₄ when used with APD detectors is the short decay time of 40 ns. This allows the use of much shorter amplifier shaping times, 0.25 μs for LSO compared to 3-20 μs for CsI(Tl) of CdWO₄, which dramatically improves the count-rate capability of the detector as well as the ratio of signal to noise