Multimodal simulation of large area silicon photomultipliers for time resolution optimization

Abstract

The Silicon Photomultiplier (SiPM) sensor is replacing the extensive use of the Photomultiplier Tube (PMT) in fast timing applications. These photo-sensors can be applied in different fields such as medical imaging systems like Positron Emission Tomography (PET), LIDAR technologies or High Energy Physics (HEP) experiments. More specific, Time-of-Flight PET (ToF-PET) requires further developments to achieve a Coincidence Time Resolution (CTR) of 10ps, this enabling the real time reconstruction and in vivo molecular examination. The most recent state-of-the-art ToF-PET systems can reach 200 ps in CTR. Lowering this value will require a cross-optimization of the scintillator crystal, the sensor and the electronics at the same time. These three elements optimization will be the key to boost the timing resolution of the complete system. The aim of this work is to provide a simulation framework that enables this cross-optimization of the PET system taking into consideration the photon physics interaction in the scintillator crystal, the sensor response (size, dead area, capacitance) and the readout electronics behavior (input impedance, noise, bandwidth). This framework has allowed us to study a new promising approach that helps reducing the CTR parameter by segmenting a large area SiPM into ?m?smaller SiPMs and then, summing the signals to recover all the signal spread along these smaller sensors. A 15% improvement on time resolution is expected by segmenting a 4 mm x 4 mm single sensor into 9 sensors of 1.3 mm x 1.3 mm with respect to the case where no segmentation is applied. The Silicon Photomultiplier (SiPM) sensor is replacing the extensive use of the Photomultiplier Tube (PMT) in fast timing applications. These photo-sensors can be applied in different fields such as medical imaging systems like Positron Emission Tomography (PET), LIDAR technologies or High Energy Physics (HEP) experiments. More specific, Time-of-Flight PET (ToF-PET) requires further developments to achieve a Coincidence Time Resolution (CTR) of 10ps, this enabling the real time reconstruction and in vivo molecular examination. The most recent state-of-the-art ToF-PET systems can reach 200 ps in CTR. Lowering this value will require a cross-optimization of the scintillator crystal, the sensor and the electronics at the same time. These three elements optimization will be the key to boost the timing resolution of the complete system. The aim of this work is to provide a simulation framework that enables this cross-optimization of the PET system taking into consideration the photon physics interaction in the scintillator crystal, the sensor response (size, dead area, capacitance) and the readout electronics behavior (input impedance, noise, bandwidth). This framework has allowed us to study a new promising approach that helps reducing the CTR parameter by segmenting a large area SiPM into ?m?smaller SiPMs and then, summing the signals to recover all the signal spread along these smaller sensors. A 15% improvement on time resolution is expected by segmenting a 4 mm x 4 mm single sensor into 9 sensors of 1.3 mm x 1.3 mm with respect to the case where no segmentation is applied.