LHCb Tracker Upgrade Technical Design Report

The upgrade of the LHCb detector will extend the physics reach of the experiment by allowing it to run at higher luminosity, ${\cal L}_{\rm inst} = 2\times 10^{33}~{\rm cm}^{-2} {\rm s}^{-1}$, with increased trigger efficiency for a wide range of decay channels. This is facilitated by the implementation of new front-end electronics, designed such that complete events can be read out and sent to the LHCb data acquisition farm for selection by a full software trigger, every 25~ns. The upgraded LHCb detector is conceived to take physics data for an integrated luminosity of at least $50~{\rm fb}^{-1}$. This Technical Design Report describes in detail the upgrade of the two tracking subsystems, located just before and just after the LHCb dipole magnet. The tracking detector before the magnet (the Upstream Tracker) will be composed of new, high-granularity silicon micro-strip planes with an improved coverage of the LHCb acceptance. Behind the magnet, a Scintillating Fibre Tracker will be built, which is composed of 2.5~m long fibres read out by silicon photomultipliers at the edge of the acceptance. The performance of the two tracking detectors and of the LHCb tracking software are presented, as well as the cost, schedule and task sharing.