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Silicon PhotoMultipliers (SiPMs) are increasingly recognized as detectors of choice for a wide range of applications due to their high photon detection efficiency, compactness, low cost and insensitivity to magnetic fields. This work demonstrates their capability to directly detect charged particles with excellent time resolution by leveraging Cherenkov radiation generated within the detector’s standard protective layer, eliminating the need for an external radiator and enabling a simple and compact detection concept.
Measurements with FBK's standard SiPMs featuring different protective layer thicknesses achieve near 100$\%$ detection efficiency, significantly exceeding the nominal geometrical fill factor. A time resolution below 20 ps, including sensor and electronic contributions, is consistently observed across devices with different active areas (1×1 mm$^2$, 3×3 mm$^2$) and microcell pitches (20, 40 $\mu$m).
Radiation tolerance studies on 1×1 mm$^2$ SiPMs show no significant degradation in time resolution up to fluences of 10$^{10}$ 1 MeV n$_\textit{eq}$ cm$^{-2}$. While radiation exposure increases the dark count rate, optimized signal thresholds can mitigate this effect, with negligible loss in detection efficiency.
Using a tracking system and charged particles, recent measurements of SiPMs without protective layers deepen the understanding of the detection mechanism and characterize detection efficiency and time resolution. Specifically, partially processed prototypes of a novel Back Side Illuminated SiPM, designed for improved performances by FBK in collaboration with INFN, exhibit promising uniform performance.
The results highlight SiPMs with standard layer as simple, versatile detectors for both photons and charged particles, combining excellent timing, high efficiency, radiation tolerance and noise rejection. Possible applications span various domains where Time Of Flight (TOF) information is important, such as High-Energy Physics (HEP) or space measurements.