Blue enhanced large area avalanche photodiodes in scintillation detection with LSO, YAP and LuAP crystals

Scintillation detectors consisting of LSO, LuAP and YAP crystals fitted to bevelled-edge large area avalanche photodiodes of 10 mm in diameter characterised by a high quantum efficiency up to 68% at 350 nm wavelength were studied. Among the properties measured were the number of electron-hole pairs, energy resolution and noise contribution of the LAAPDs at shaping time constants down to 20 ns at different gains. High electron-hole pair numbers of 11000±550 e-h/MeV and 19500±980 e-h/MeV for the YAP and LSO crystals were measured, respectively. The energy resolution for ¹³⁷Cs γ-rays of 5.9% in FWHM for the YAP crystal, much better than that of 9.9% for the LSO crystal were measured at 0.5 μs shaping time constant and the APD gain of 40. The same study done with a fast shaping of 20 ns and the APD gain of 160 showed the energy resolution of 6.7%