Avalanche photodiodes in scintillation detection

This paper summarizes our studies on performance of Large Area Avalanche Photodiodes (LAAPDs) in gamma rays scintillation detection. Produced by Advanced Photonix, Inc. LAAPDs, because of their high sensitivity, low excess noise and large active area can potentially replace small area photomultiplier tubes (PMTs) in readout of scintillators. l inorganic scintillators have been used to evaluate performance of commercially available LAAPDs as light readout devices in gamma-ray spectroscopy and timing measurements. The main factors limiting energy resolution have been analyzed and the experimental results have been compared with those obtained with PMT readout. Notably better or comparable energy resolutions to those observed with a XP2020Q photomultiplier were obtained with the LAAPDs for a number of different scintillators. Particularly, the recorded energy resolutions of 4.3±0.2% and 4.8±0.14% measured with YAP and CsI(Tl) crystals, respectively, for the 662 keV γ-peak from a 137Cs source belong to the best observed ever with these scintillators. Results of the study of timing with fast scintillators coupled to the LAAPDs showed subnanosecond time resolution of 570 ps for 60Co γ-rays detected with LSO crystal.