Characterization of SiPMs after radiation damage

Silicon PhotoMultipliers (SiPMs) are light detectors with sensitivity to single photons. Thanks to their excellent performance (high gain and low noise), their robustness and insensitivity to magnetic fields, they find many applications in high energy physics experiments and many other fields. For applications in collider experiments one of the major limitation is due to radiation damage. This talk present characterization procedures for SiPMs irradiated with reactor neutrons to fluences up to 10${}^{14}$ cm${}^{-2}$. The measurements are performed in a controlled climate chamber, which can reach a temperature of 50°C. Blue pulsed laser light is used to illuminate the SiPM and the waveform recorded using a 2.5 GHz oscilloscope to investigate the signal response and the gain. The increase of dark count rate and noise, and the decrease of signal of the irradiated SiPMs, as a function of the fluence, operational temperature and voltage are determined, and compared with results obtained by an analysis of the current-voltage characteristics of the same SiPMs. Moreover, it has been made also a detailed simulation of the SiPM, allowing a further comparison and comprehension of the results.