Speaker
Description
The LHCb experiment at CERN plans to have a major upgrade, the so called LHCb Upgrade II, in order to increase the instantaneous luminosity at the LHCb interaction point to ~1.5 x 10^34 cm^-2s^-1 starting from 2035. Increasing the luminosity by a factor of ~7 compared to the current experiment requires major upgrades to the LHCb detectors. Part of the LHCb Upgrade II project is the replacement of the present RICH photon detectors (MAPMTs) with sensors which can guarantee optimal particle identification performance at the High-Lumi conditions. This is a challenging task since the photo-sensors must have single photon detection capability and good spatial and time resolution in a very high radiation environment.
SiPM is a candidate technology, given the small dimensions, fast response, high detection efficiency and relatively low cost. Their main drawback is the dark count rate which increases rapidly with radiation but can be mitigated by lowering their working temperature. Extensive studies are ongoing to understand how their performance degrade with radiation and how they recover with annealing at higher temperature.
In this work we will present the full characterization of 45 commercial SiPMs (MPPCs) from Hamamatsu Photonics, model 13360-13xxPE, of three different micro-cell sizes: xx=25, 50 and 75um and with an active area of 1.3 x 1.3 mm^2. For each device, results will be presented for the direct and reverse I-V curves, the gain, the DCR and the time resolution, measured at five temperature steps, from room temperature down to the liquid Nitrogen temperature. After the initial characterization, the SiPMs were irradiated at the TRIGA II reactor in Ljubljana at five neutron fluences steps, from 3 x 10^11 up to 6 x 10^13 1MeV-neq. After the irradiation the SiPM were characterized again, to quantify the degradation of the parameters as a function of the fluence and of the temperature. Results will be presented, together with first measurements after a subsequent annealing campaign.