Speaker
Description
Silicon sensors are widely employed in modern physics experiments in both tracking detectors and photo-detection systems. Silicon photomultipliers (SiPMs) are increasingly adopted for their excellent photon detection efficiency, fast timing, scalability, and insensitivity to magnetic fields. A first application of SiPMs for single-photon detection in a collider experiment will be for the dual-radiator (dRICH) detector of the ePIC experiment at the future Electron-Ion Collider (EIC). The dRICH photodetector will cover ~3 m$^2$ with 3x3 mm$^2$ pixels, for a total of more than 300000 readout channels and will be the first application of SiPMs for single-photon detection in a collider experiment. The SiPMs excellent performance is challenged by radiation damage arising from the high particle fluxes typical of hadron collider environments. Ionising and non-ionising radiation introduces defects in the silicon lattice, which manifest as increased dark count rate, ultimately degrading single-photon sensitivity.
As radiation-induced defects act as generation-recombination centres in the silicon lattice, light is emitted from these defects and can be spotted taking pictures of the device with a high-performance camera. We complement the traditional electrical characterization of SiPMs after irradiation with an optical characterization of the sensors, using emission microscopy to directly visualise radiation-induced defects in the silicon lattice and their evolution with detector operational parameters (temperature and bias voltage), irradiation damage, and recovery from annealing. This combined methodology provides deeper insight into the nature and localisation of the damage, offering a more comprehensive understanding of its impact on SiPMs performance.
In this talk, the microscope setup and the first results will be presented. Pictures taken before and after irradiation with protons and neutrons at a fluency of ~10$^9$ n$_{eq}$/cm$^2$, and after annealing cycles, show the evolution of the defects in the Hamamatsu SiPM sensors under study.
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