Timing performance of FBK SiPM NUV-HD-MT technology using LYSO:Ce:Ca crystal

The need to push the timing performances to the limit finds breeding ground in several fields from high energy physics to biomedical applications such as Time of Flight Positron Emission Tomography (ToF-PET). In the last years, excellent results have been achieved thanks to the improvement of the scintillator crystal materials, the electronics readout and the detector development. In this context, SiPM Coincidence Time Resolution (CTR) is a key parameter in order to assess the device timing performance. In this work we will present the CTR of the recently introduced FBK NUV-HD-MT Silicon Photomultiplier (SiPM) technology. Thanks to the addition of the optically insulating material inside the trenches, FBK NUV-HDMT devices show an extremely low CrossTalk (CT) of about ≃ 5% at 47.5V (≃ 15V excess bias). The Photon Detection Efficiency (PDE) reaches the ≃ 65% at the same excess bias at 420nm. The CTR was measured using a 4mm × 4mm SiPM to match the 3mm × 3mm × 5mm LYSO:Ce:Ca crystal and comparing different microcell sizes. By using a standard readout electronics we achieved a CTR of ~ 95ps FWHM for all the devices thanks to the extremely low CT of the technology that allows to push the voltage bias to high values. We also compare the CTR between the SiPM version with a metal mask outside the active area (capacitive coupling) and the SiPM without it in order to asses the role of the masking in the timing performance, to discuss about limitations and further improvements.