An Asynchronous Level-1 Tracking Trigger for Future LHC Detector Upgrades

An asynchronous Level-1 trigger system for future LHC upgrades is proposed. A small-scale prototype of such system has been developed and tested. As the beam-crossing frequency increases in a future LHC upgrade (SLHC), and more data is brought into the Level-1 trigger system, the synchronization of the traditional synchronous trigger system composed of thousands of cards will become even more difficult. To demonstrate the advantages of asynchronous trigger designs, we have developed an upgrade of the front-end trigger electronics of three spare cathode-strip chambers (CSCs) of the CMS endcap muon system to perform pattern recognition and bunch-crossing assignment from the anode data at 80 MHz frequency. Trigger primitives from up to 3 chambers are transmitted via 10 Gb/s serial links to a newly designed track-finder processor - a PC plug-in card. Once a track is found, it generates the asynchronous Level-1 accept signal with time marker that is sent back to front-end boards. Preliminary test results from components of the prototype system are reported.