Multichannel optical fiber distribution system for LHC detector timing and control signals

To synchronize the front-end electronics of experiments at the Large Hadron Collider (LHC), clock signals derived from the machine's radio-frequency system must be distributed to thousands of destinations located within a detector volume of up to 9500 m/sup 3/. The signals delivered to different groups of channels must be phase-compensated with subnanosecond precision for particle flight times and delays due to detector processes, electronics, and cable propagation. A multichannel optical fiber network for timing signal distribution could simultaneously be exploited for the broadcasting of trigger-accept and control signals and the transmission of addressed digital data such as deskew parameters and virtual pipeline address offsets. Two research and development projects are currently exploring various aspects of this concept, including studies of appropriate high-power fiber-coupled laser transmitters and their modulators, coding, passive optical tree couplers, low-cost optoelectronic receivers, programmable delay technologies, and system integration with the level-1 central trigger processor.<>