During the Long Shutdown 2 of the LHC, the LHCb collaboration will replace the upstream
Ring Imaging Cherenkov detector (RICH 1). The magnetic shield of the current RICH 1
will be modified, new spherical and plane mirrors will be installed and a new gas enclosure
will be manufactured. New photon detectors (multianode photomultiplier tubes) will be
used and these, together with their readout electronics, require a new mechanical support
system. This document describes the new optical arrangement of RICH 1, its engineering
design, installation and alignment. A summary of the project schedule and institute
responsibilities is provided