Speaker
Description
Readout circuits for large-area Silicon Photomultiplier (SiPM) arrays coupled to scintillators are in use for homeland security applications, where high sensitivity is essential. High sensitivity is achieved by increasing the scintillator volume, which requires enlarging the SiPM area, and by adding additional scintillators, which in turn requires adding more SiPMs. Individual readout of SiPM arrays offers the best performance for energy and spatial resolution; however, as the number of SiPMs increases, so do the required space, power consumption, and data transmission bandwidth of the data acquisition system.
Multiplexed readout circuits, which reduce the number of readout channels, may especially benefit for remote and cost-effective devices such as directional radiation detectors and Radiological Dispersal Devices (RDD). Large SiPMs pose unique challenges in multiplexed readout circuits due to increased capacitance which increases decay time, and increased dark current, which lowers the signal-to-noise ratio. Consequently, energy resolution degrades, and Flood Histogram distortion rises, causing the spatial resolution to decrease. Although extensive research has focused on multiplexed readout circuits in nuclear medicine applications, primarily involving small SiPMs with rapid decay times, research for large-area SiPMs is limited.
In this study, we’ve simulated, developed, and evaluated four classical multiplexing circuits: Anger logic, Discretized Positioning Circuit (DPC), resistor-based Symmetric Charge Division (SCD), and diode-based SCD. Those circuits were optimized by simulations for an array of 64 SiPMs, each with an area of 12.64 × 12.64 mm2, coupled to a CsI(Tl) scintillator. The developed circuits were evaluated in terms of energy resolution, energy linearity, and spatial resolution. Our extensive research demonstrated that the diode-based SCD circuit outperforms the others, offering higher energy and lower spatial resolution distortion.
