CMS Inner Tracker upgrade for the HL-LHC: Design, development, and production status

The High Luminosity Large Hadron Collider operation will push the CMS experiment to its limits, with an instantaneous peak luminosity of 7 . 5 × 1 0 34 cm − 2 s − 1 and an integrated luminosity of 300 fb − 1 per year. This environment will expose the CMS Inner Tracker (IT) pixel detector at the center of CMS to unprecedented levels of radiation, with a 1 MeV neutron equivalent fluence of Φ eq = 2 . 6 × 1 0 16 cm − 2 and a total ionizing dose of 13 MGy after 3000 fb -1 of integrated luminosity. To endure these conditions and handle hit rates of 3 . 2 GHz / cm 2 while managing a pileup of 140 to 200 collisions per bunch crossing, the new IT system will employ a highly granular design with thin silicon sensors, small pixels (25 × 100 μm 2 ), and fast, radiation-hard electronics based on a 65 nm CMOS ASIC developed by the RD53 collaboration. A novel serial powering scheme and high-bandwidth readout system will support the upgraded modules, while lightweight carbon-fiber mechanics with two-phase CO 2 cooling will ensure structural integrity. The design will extend the tracking coverage up to | η | ≈ 4 . This contribution presents an overview of the CMS IT upgrade project, focusing on the ongoing activities and status of the module production of all the IT subsystems.