Determining the Photon Yield of the LHCb RICH Upgrade Photo-Detection System

For the upgrade of the LHCb RICH detectors in 2020 the existing photon detection system will be replaced. This study investigates the photon yield of the multianode photomultiplier tubes (MaPMTs), which have been proposed as the new photon detectors, together with the associated readout electronics. Data collected using the LHCb RICH Upgrade test beam in autumn of 2016 are used. Four MaPMTs were exposed simultaneously to Cherenkov light generated in a solid radiator by a charged hadron beam of 180 GeV. A simulation of the test beam set up was created using the Geant4 toolkit. Comparing the number of detected photoelectrons from each incident charged particle in data and simulation allows the detection efficiency of the photon detection system to be determined.