Delfo Nunziato Sanfilippo

Crosstalk Characterization in Geiger-Mode Avalanche Photodiode Arrays

Following our work on Geiger-mode avalanche photodiode arrays, we have recently been dealing with the crosstalk issue in newly developed dense arrays with a minimum distance between pixel centers of 84 mum. In this paper, we present our crosstalk measurement approach, including the experimental setup and the offline calculation methods. Different characterizations of the crosstalk probability PCT versus capacitance have been performed to extrapolate the PCT when no measurement setup loads the pixels. We also present results regarding the crosstalk probability versus pixel distance and bias. Moreover, by adopting a slightly different approach, the probability density decay time has been measured to investigate about crosstalk origin.

Timing performance comparison of P-on-N and N-on-P silicon photomultipliers

We have investigated the timing performance of P-on-N and N-on-P silicon photomultipliers (SiPM) in light of their use in time-of-flight (TOF) positron emission tomography (PET) detectors. Polished 3 mm × 3 mm × 5 mm and 3 mm × 3 mm × 20 mm LYSO:Ce scintillators were coupled to STmicroelectronics P-on-N and N-on-P SiPMs. The SiPMs were read out with low-noise RF transimpedance amplifiers and fed to a waveform digitizer for offline time pickoff analysis. For the P-on-N devices coincidence resolving times (CRTs) of 234 ps and 189 ps FWHM were obtained with the 3 mm × 3 mm × 20 mm and 3 mm × 3 mm × 5 mm crystals, respectively. For the Non-P devices CRTs of 280 ps and 214 ps FWHM, respectively, were obtained with above crystal types. The P-on-N devices are promising for TOF-PET due to their high photon detection efficiency (PDE) and low transit time spread (TTS).