Design and construction of the CMS Outer Tracker for the HL-LHC Upgrade

The High Luminosity LHC (HL-LHC) is expected to deliver an integrated luminosity of 3000–4000 fb−1 with the peak instantaneous luminosity reaching to about 5–7.5 × 1034 cm−2s−1. During the Long Shutdown 3 period, several components of the CMS detector will undergo major changes, called Phase-2 upgrades, to be able to operate in the challenging environment of the HL-LHC. The current silicon strip tracker has to be replaced for operation in the HL-LHC period. The Phase-2 Outer Tracker will have high radiation tolerance, higher granularity, and the capability to handle higher data rates. Another key feature will be the ability to provide tracking information to the Level-1 trigger, allowing trigger rates to be kept at a sustainable level without sacrificing physics potential. For this, the Outer Tracker will be made out of modules that have two closely spaced silicon sensors read out by a common front-end ASIC, which can correlate hits in the two sensors creating short track segments, called stubs. The stubs will be used to reconstruct tracks in the Level-1 track finder. In this contribution, the design of the CMS Phase-2 Outer Tracker, the technological choices, and first results with pre-production devices will be reported focussing on the detector modules.