Jet determination in liquid argon calorimeters using a heavily interconnected system of field programmable gate arrays

New fast and highly complex Field Programmable Gate Arrays (FPGAs) allow the design of sophisticated decision logic within the trigger latency time of particle detectors. As an example we show the jet determination of the Hera-Hl detector at DESY (Deutsches Elektronen Synchrotron) Hamburg. It has to calculate all existing localized energy depositions (jets) in the calorimeter and deliver the result, sorted according to energy. The system is implemented by a network of 3×440 high density FPGA´s which have to deliver the results in less than 1 μs. The computing power of the system is equivalent to 70 billion operations per second