Analog filtering methods improve leading edge timing performance of multiplexed SiPMs

Area of Science:

• Medical Imaging
• Instrumentation
• Physics

Background:

• Multiplexing many Silicon Photomultipliers (SiPMs) to a single readout channel reduces complexity in high-performance Time of Flight Positron Emission Tomography (TOF PET) systems.
• Baseline fluctuations from dark counts and shaping in multiplexed SiPMs degrade timing measurements using leading-edge threshold techniques.

Purpose of the Study:

• To introduce a simple analog filtering network to mitigate baseline fluctuations in highly multiplexed SiPM readouts.
• To evaluate the impact of this filtering technique on timing resolution in TOF PET systems.

Main Methods:

• Development and application of a simple analog filtering network for SiPM readout.
• Testing with 16 SiPMs multiplexed to a single channel using LYSO crystals.
• Testing with 4 SiPMs multiplexed using LFS crystals.
• Acquisition of position information using a novel binary positioning network.
• Experiments conducted at room temperature without active temperature regulation.

Main Results:

• Full Width at Half Maximum (FWHM) coincident timing resolution improved from 401 ± 4 ps to 248 ± 5 ps with 16 multiplexed SiPMs and LYSO crystals.
• Mean time resolution improved from 436 ± 6 ps to 249 ± 2 ps with 4 multiplexed SiPMs and LFS crystals.
• Successful acquisition of position information demonstrated.

Conclusions:

• The analog filtering network effectively reduces baseline fluctuations in multiplexed SiPM readouts.
• This technique offers a promising approach for constructing high-performance multiplexed TOF PET systems.
• Analog leading-edge timing pickoff is viable for advanced TOF PET instrumentation.