Studies and Validation of a CMS Drift Tube Trigger Algorithm for HL-LHC

The electronics of the CMS (Compact Muon Solenoid) DT (Drift Tubes) chambers will need to be replaced for the HL-LHC (High Luminosity Large Hadron Collider) operation due to the increase of occupancy and trigger rates in the detector, which cannot be sustained by the present system. A new system is being designed that will forward asynchronously the totality of the chamber signals to the control room, at full resolution. A new back-end system will be in charge of building the trigger primitives of each chamber out of this asynchronous information, aiming at achieving resolutions comparable to the ones that the offline High Level Trigger can obtain nowadays. In this way, the new system will provide better functionality with respect to the present system, allowing to improve the resilience to potential aging situations. An algorithm, called the Analytical Method (AM), has been designed for this new backed system following a simplified, hardware-oriented procedure optimizing the FPGA resources. The performance of this algorithm has been validated through different methods: from a software emulation approach to hardware implementation tests. The performance obtained is very good, with optimal timing and position resolutions, close to the ultimate performance of the DT chamber system. One important validation step has included the implementation of this algorithm in a prototype chain of the HLLHC electronics, which has been operated with real DT chambers under cosmic data taking campaigns. The new trigger primitive generation has been implemented in spare uTCA boards from the present DT system which host Xilinx Virtex 7 FPGAs. The performance of this prototyping/algorithm has been verified and will be presented in this contribution.