Timing resolution studies of irradiated SiPMs for the ALICE 3 experiment

ALICE 3 is a next-generation multipurpose detector, designed as an upgrade of the present ALICE experiment for the LHC Runs 5-6. To enable the physics programme which aims at studying the properties of Quark-Gluon Plasma, ALICE 3 features high readout rate capa- bilities, superb pointing resolution and excellent tracking and particle identification over a large acceptance. One of the main requirements for the PID system is a Time-Of-Flight (TOF) detector for time measurements with 20 ps resolution. Silicon PhotoMultipliers (SiPMs) are among the possible candidates for the outer layer of the TOF detector, due to their high efficiency and their capability to directly detect charged particles thanks to the Cherenkov light produced through the standard protection layer of the SiPM. SiPMs of 1 × 1 mm^2 area with 1 mm and 1.5 mm silicone protection were studied in this context to evaluate their performance before and after irradiation: indeed, their performances were previously studied in beam test at CERN-PS and after being irradiated with 10^9 and 10^{10} MeV n_{eq} cm^{−2} it is shown that, thanks to the very high signal detected on the SiPM at the passage of a charged particle, the sensors maintain an excellent time response. Even if DCR gets higher with respect to new SiPMs, a high noise rejection can be obtained once an appropriate threshold is applied to the signal. These studies on the possibility to use SiPMs as particle detectors are crucial for their possible future applications in many areas.