Speaker
Description
The dual-radiator Ring-Imaging Cherenkov (dRICH) detector of the ePIC experiment at the future Electron–Ion Collider (EIC) will employ silicon photomultipliers (SiPMs) to detect Cherenkov photons. The photodetector plane will span about 3 m2 with 3x3 mm2 pixels, providing more than 300 000 readout channels—representing the first use of SiPMs for single-photon detection in a collider environment. SiPMs were selected for their high photon-detection efficiency and competitive cost, as well as for their insensitivity to the strong magnetic field at the dRICH location (~1 T).
Because SiPMs are not inherently radiation-hard, maintaining their single-photon performance and controlling the dark count rate (DCR) over the lifetime of ePIC requires dedicated mitigation strategies. These include operating at low temperature, periodic high-temperature annealing to recover radiation damage, and exploiting precise timing with fast TDC electronics to suppress DCR-induced background and improve the signal-to-noise ratio.
This contribution presents an overview of the ePIC-dRICH photodetector system and highlights results from the R&D programme for SiPM operation in ePIC. Particular emphasis is placed on the development and beam-test performance of a large-area prototype readout plane comprising up to 2048 3x3 mm2 SiPM sensors. The modular prototype is based on a novel EIC-driven photodetection unit (PDU) developed by INFN, integrating 256 SiPM pixels, cooling, and TDC electronics in a compact 5x5x14 cm³ volume. Several PDU modules have been assembled and successfully tested with particle beams at the CERN PS in October 2023 and May 2024, using a complete readout chain based on the ALCOR front-end chip developed by INFN Torino.
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