Performance Comparison of Different Readouts for Position-Sensitive Solid-State Photomultiplier Arrays

Area of Science:

• Instrumentation and Measurement
• Nuclear Science and Engineering
• Detector Physics

Background:

• Position-sensitive solid-state photomultipliers (PS-SSPMs) are critical components in various scientific instruments requiring precise spatial and timing information.
• Evaluating different readout methods is essential for optimizing detector performance and tailoring solutions for specific application needs.
• The performance of PS-SSPMs is influenced by factors such as signal processing, bias voltage, and temperature.

Purpose of the Study:

• To conduct a comprehensive comparison of five distinct readout methods for a 2x2 array of PS-SSPMs.
• To evaluate the impact of different readouts on key performance metrics including flood histogram quality, signal-to-noise ratio (SNR), and energy resolution.
• To determine the optimal readout strategy for ultra-high spatial resolution applications versus cost-effective solutions.

Main Methods:

• Five readout strategies were tested: individual signal readout, two signal multiplexing readouts, and two position decoding readouts.
• Performance was assessed by coupling a 6x6 array of LSO crystals to the PS-SSPM array and measuring flood histogram quality, SNR, and energy resolution.
• Measurements were performed across a range of bias voltages (27.0 V to 32.0 V) at a fixed temperature of 0 °C, with timing resolution measured at optimal bias voltage.

Main Results:

• Individual readout of all 20 signals (16 position, 4 timing) yielded the best flood histogram quality (7.3 ± 1.6) and SNR (33.5 ± 3.1).
• The capacitive charge-division readout, the simplest method, demonstrated good performance with a flood histogram quality of 3.3 ± 0.4 and SNR of 18.3 ± 1.3.
• Average energy resolution was 15.2 ± 1.2% and timing resolution was 8.4 ± 1.6 ns for individual readout, compared to 15.9 ± 1.2% and 8.8 ± 1.3 ns for capacitive charge-division.

Conclusions:

• For applications demanding ultra-high spatial resolution with a 2x2 PS-SSPM array, individual readout of all signals is necessary.
• The capacitive charge-division readout offers a viable, cost-effective alternative for applications with less stringent spatial resolution requirements.
• The choice of readout method significantly impacts PS-SSPM performance, allowing for tailored detector designs based on application needs.