Proposal for LHCb RICH detector enhancements during LHC Long Shutdown 3

The prompt Cherenkov radiation and focusing optics of the RICH detectors result in time characteristics which are unique among large-volume detector systems. The time-of-arrival at the photon detectors of the Cherenkov photons corresponding to a given primary vertex can be predicted to within ten picoseconds. This property can be used to significantly improve the signal to noise ratio and thereby the PID performance of the detector and will ultimately allow the present system to withstand luminosities in excess of $10^{34}cm^{-2}s^{-1}$. To this end, we propose to integrate a new readout ASIC, the FastRICH, into the present system during the Long Shutdown 3 (LS3, 2026-2028). This will allow the system to timestamp each photon with an approximately 150 ps time resolution within a short gate of about 2 ns. This enhancement can be achieved at a limited cost, prepares for the Upgrade II RICH system overhaul and improves the hadronic PID performance for the physics programme of LHCb during Run 4.