The LHCb Collaboration is planning a major "Upgrade II" of the experiment with the purpose to increase the instantaneous luminosity by a factor of 5 to 1.5x10$^{34}$cm$^{-2}$s$^{-1}$ during Long Shutdown 4 of the LHC. This poses stringent requirements on the capabilities of subdetectors due to the increased particle multiplicity and detector occupancy. The Upgrade II LHCb RICH (Ring-imaging Cherenkov) subsystem will require improvements in spatial and time resolution to maintain good particle identification performance in this environment.
To address these challenges, an improvement in the readout electronics is planned during the Long Shutdown 3 (LS3), from 2026 to 2028. The goal is to timestamp the data with an accuracy better than O(100) ps from Run4 (2029-2032) onwards, in parallel with the development of novel sensors capable of sub-100 ps time resolution for Run5 (2035-2038). The LS3 enhancements foresee the use of the FastRICH, a 65-nm CMOS front-end readout chip, under development by CERN and ICCUB. In these proceedings a prototype opto-electronic chain for Cherenkov photon detection with precise-timing is presented as a proof-of-principle for the future RICH detectors. This readout chain is equipped with the FastIC, a precursor to the FastRICH with a similar dynamic range.
In order to evaluate the time resolution of the prototype photo-detection chain equipped with the FastIC chip, beam test campaigns were conducted in 2021 and 2022 at CERN SPS charged particle beam facility with 180 GeV/c protons and pions.
The results of such beam tests are presented, with a focus on the final results coming from the timing analysis and on the corrections applied to account for the time-walk effect.