Comparative study of avalanche photodiodes with different structures in scintillation detection

The performance of beveled-edge large-area avalanche photodiodes (LAAPDs) produced by Advanced Photonix, Inc. (API), Hamamatsu SPL 2560 APDs, and APDs from the Institute of Electron Technology (ITE) was studied in scintillation detection using CsI(TI), BGO, LSO, and YAP scintillators. Measurements covered dc gain characteristics, relative response to X-rays and light, and energy resolution for 5.9-keV X-rays from a [sup.55.]Fe source. We also determined the electron-hole (e-h) pair numbers for the studied scintillators and the detector energy resolution for 662-keV [gamma]-rays from a [sup.137.]Cs source. The highest numbers of e-h pairs were measured with the LAAPD equaling 33 800 e-h/MeV for CsI(TI) and 10200 e-h/MeV for the YAP crystal. In the case of the Hamamatsu APD, the respective numbers were 30 900 e-h/MeV and 4700 e-h/MeV. Finally, the APD from ITE measured 16 500 e-h/MeV with CsI(TI). The best energy resolution of 4.9% for 662 keV was observed with CsI(TI) coupled to the LAAPD. The second best resolution was with the Hamamatsu APD showing a result of 5.8%. Index Terms--Avalanche photodiodes, energy resolution, scintillation detection.