Quality assurance for the LHCb RICH upgrade Photon-Detection chain

Abstract

During the Long Shutdown 2 of the LHC, the LHCb RICH system has undergone an upgrade to implement the LHCb trigger strategy which increased the read-out rate from 1 MHz to 40 MHz. The new challenging operating conditions of the upgraded experiment required the replacement of the Hybrid Photon Detectors with Multi-Anode Photomultiplier tubes (MaPMT) and the introduction of new customised front-end electronics. The new RICH detectors have a modular design to facilitate maintenance and assembly. The fundamental core element is the Elementary Cell (EC), which is composed of one or four MaPMTs, depending on the type of the MaPMT, and the associated front-end electronics. An overview of the protocols and testing facilities which have been designed and put in place to perform the quality assurance programme is presented. This process lasted more than six years and included the testing and characterisation of the new front-end electronics, the MaPMTs, the ECs, and the photon detector assembly (columns), commissioning, and installation of the columns in the LHCb cavern.