First results from a prototype level-1 calorimeter trigger system for LHC

As part of the RD27 collaboration, we have studied the problem of level-l calorimetric triggering and have developed an algorithm to identify electromagnetic energy clusters. This algorithm has been incorporated into a prototype CMOS Application-Specific Integrated Circuit (ASIC) running as a pipelined processor at up to 67 MHz. In order to verify the operation of the processor in a realistic enviromnent, a multi-ASIC demonstrator system has been constructed and used to instrument small regions of two prototype electromagnetic calorimeters in CERN test beams. We present here details of the demonstrator system and analysis of the data which have been taken so far. The results show that the demonstrator system performs successfully and recognises electromagnetic clusters efficiently at LHC rates. To realise a complete level—1 trigger system several further areas require study. In particular, data bandwidth must be minimised by using sparsification techniques, and I/O requirements reduced by serialisation. These approaches imply the use of asynchronous systems, the features of which we intend to study in the next phase of this work.