PlatonSPAD: A novel SPAD sensor for large-scale high-resolution particle detectors

TL;DR

PlatonSPAD addresses the challenge of large-scale, high-resolution particle detection by employing CMOS SPAD arrays with an event-driven readout architecture. The authors optimize SPAD layouts to balance photon detection efficiency and dark count rate, formalized as PDE = PDP × FF, and demonstrate a 4×4 macropixel module with two 200 ps LSB TDCs and a tunable Δt delay to capture two timestamped events within a 5 μs window. Key results show DCR around 1 cps/μm^2 at 7 V excess bias and PDE up to ~40% near 460 nm, with substantial PDE gains from layout improvements while preserving low noise; the system can produce two sub-images with corresponding timestamps, matching scintillator decay times. This work advances the feasibility of large-scale SPAD-based detectors for neutrino experiments and outlines a path toward full-scale PlatonSPAD sensors, addressing synchronization, crosstalk, and data acquisition for future deployments.

Abstract

High-resolution 3D tracking with sub-nanosecond timing is required for the detection of elementary particles, such as neutrinos. Conventional detectors, which utilize analog silicon photomultipliers, face challenges in balancing spatial resolution and scalability. To address this issue, a CMOS single-photon avalanche diode (SPAD)-based high-resolution particle detector is being developed. This work presents a study on SPAD layout optimization and a 4x4 SPAD macropixel module, fabricated in 110 nm CIS technology. Measurement results confirm that high-fill-factor designs improve photon detection efficiency without significant noise degradation. Furthermore, event-driven photon mapping and time stamping, enabled by time-to-digital converters and dedicated pixel circuits integrated into the 4x4 SPAD macropixel, were successfully demonstrated. This work is an essential step towards a sensor that detects probabilistic particle interactions and it lays the groundwork for the development of future large-scale SPAD-based particle detectors.

Figures (10)

• Figure 1: Picture of the SuperFGD detector showing its dimensions. Sgalaberna2024Blondel2018
• Figure 2: Concept of PlatonSPAD, the large-scale high-resolution particle tracking system.
• Figure 3: Cross-section and layout variations of the SPADs in 110 nm CIS Technology. Karaca2024
• Figure 4: System overview of the designed 4×4 SPAD Sensor micropixel module. (a) Example of the measurement timeline in a neutrino detection experiment. (b) Circuit overview of the 4×4 SPAD Sensor micropixel module.
• Figure 5: Pixel circuit of 4×4 SPAD Sensor micropixel module.