Prospects for future upgrade of the LHCb RICH system

The LHCb experiment has collected data corresponding to 6.9 fb-1 of integrated luminosity since 2010 and the two RICH detectors have been essential for most of the LHCb physics programme. Preparations are underway to install an upgraded RICH detector so that from 2021 onwards LHCb can collect data corresponding to 5 fb-1 of integrated luminosity per year in order to improve the statistical precision of the physics measurements and to search for very rare B-decays and D-decays. For this, the current Level 0 hardware trigger running at 1 MHz will be removed so that detectors can be read out at at the full collision rate of 40 MHz. The long term physics goals of LHCb calls for a further upgrade of the detector system for collecting data corresponding 50 fb-1 of integrated luminosity by 2029 and 300 fb-1 afterwards. The first set of such upgrades are envisaged for the run starting in 2026 where the luminosity in LHCb continues to be 2X1033 cm-2s-1 as in the preceeding years. For the run from 2030 onwards the luminosity in LHCb is planned to be 2X1034 cm-2s-1 and this will result in about 35 interactions per LHC bunch crossing. Hence the detectors would require a major upgrade to cope with the high occupancies resulting from the increased particle multiplicity. Feasibility studies are underway for recording the time of arrival of the RICH hits in addition to their spatial coordinates on the detector plane. The complexity of the event can be reduced by removing hits outside the signal time window and by separating out the hits created by tracks which originated in different primary vertices. Incorporating the RICH hit time information can also improve the performance of the particle identification algorithm.This requires using photon detectors with fast readout. The feasibility of this is expected to be tested using prototypes. Using a photon detector with increased quantum efficiency in the green, like a SiPM(silicon photomultiplier), one can help to improve the chromatic error without reducing the photon yield. Measures to improve the optical configuration of the RICH detectors and to improve their pixel granularity are being investigated. Extending the momentum range to improve the performance in the 1-10 GeV/c range and in the range above 70 GeV/c is also explored. One option for this is to develop novel radiators based on photonic crystals. An overview of all these developments will be presented. This will include the expected performances and the status of the feasibility studies from simulations and prototype testing