The upgrade II of the LHCb RICH System

The Ring Imaging Cherenkov (RICH) detectors of the LHCb experiment have provided charged hadron identification over a wide momentum range since the start of data taking at the LHC. After a first major upgrade currently operating in LHC Run 3, the LHCb experiment foresees a second, more ambitious “Upgrade II” to operate at five to seven times higher instantaneous luminosity starting from Run 5. The RICH system will face unprecedented challenges in terms of photon rates, radiation, timing requirements and mechanical constraints, while aiming to maintain the same or better particle identification (PID) performance. This paper provides an overview of the LHCb RICH Upgrade II programme, summarising the main detector requirements and the ongoing R&D activities on photon detectors, cooling, optics and fast electronics.