The Phase-2 Upgrade of the CMS Outer Tracker

The Large Hadron Collider at CERN will undergo a major upgrade in the Long Shutdown 3 from 2026 to 2028. The High Luminosity LHC is expected to deliver peak instantaneous luminosities up to 7.5E34/cm2/s and an integrated luminosity in excess of 3000/fb in the following ten years of operation. In order to fully exploit the delivered luminosity and to cope with the demanding operating conditions, the entire silicon tracking system of the CMS experiment will have to be replaced. The Phase-2 Outer Tracker (OT) will have an increased radiation hardness, a higher granularity, and will be able to cope with larger data rates. A key feature of the CMS tracker upgrade is the inclusion of charged particle trajectories in the hardware-based (L1) trigger system. A 40 MHz silicon-based track trigger on the size of the CMS detector has never before been built; it is a novel development with the potential to not only solidify the CMS trigger strategy but to enable searches for completely new physics signatures. To achieve this, each module consists of two closely spaced sensors that are connected to the same set of readout chips. The readout chips correlate data from both sensors for a rough transverse momentum measurement. This concept will allow the trigger rates to remain at sustainable levels without sacrificing physics potential. The design of the CMS Phase-2 Outer Tracker will be presented, along with highlights from the upgrade prototyping activities.