Upgrade of the CMS Drift Tube system for the High Luminosity LHC

Abstract The Large Hadron Collider (LHC) will undergo a major upgrade during its third Long Shutdown period, after which the High-Luminosity LHC era will begin. During the HL-LHC phase, proton-proton collisions are expected to be delivered at 5 to 7 times the nominal LHC instantaneous luminosity. Also, the number of collisions per proton bunch crossing will reach values up to 200. The CMS experiment will undergo a substantial upgrade as well. The harsher radiation environment and the much higher number of overlapping events will require CMS to upgrade both the detector technologies and electronics. The Drift Tubes (DT) chambers — the muon detectors instrumenting the barrel region — will remain the same throughout the HL-LHC era. However, legacy detector readout and trigger electronics are not capable of sustaining the trigger rate, which is expected to increase from present 100 kHz up to 750 kHz, and to tolerate the higher levels of radiation. The new On-detector Board for DT (OBDT) will primarily perform time-to-digital conversion forwarding up to 240 time digitization channels to the back-end system without data losses. A new back-end system will implement the DT trigger primitive algorithm capable of using the OBDT streamline data and performing the DT muon track reconstruction in the available latency and with a resolution similar to offline. A small fraction of the DT chambers have been already operated in parallel with both legacy and upgraded electronics during Run 3 data-taking. This early integration enabled CMS to validate the new electronics and evaluate its performances. This report will give an overview of the status of the DT electronics upgrade as well as a report on the upgraded electronics performance using latest Run 3 proton-proton collision data.