ATLAS Level-2 Trigger Demonstrator-A Activity Report Part 1: Overview and Summary

The demo-A activity report describes the work done on the ATLAS Level-2 trigger during the recent phase of the demonstrator program by the groups associated with architecture-A: Cracow, Jena, Mannheim and Weizmann. Important contributions by CERN (Rudy Bock et. al.) and from the Saclay architecture-C group are included. The activity report is presented in a set of three separate documents: Part 1: Overview and summary Part 2: Measurements and results Part 3: Paper model This first part gives an overview of the trigger system and the target architecture-A. The evolution of this FPGA based trigger approach towards a hybrid system is illustrated. The key element of architecture-A - the FPGA-processor - is presented with it’s most important features. A description of all components used in the demonstrator-A program together with a result summary is given. Next the focus of the activities concerning FPGA based processing during the pilot project is explained. Finally some conclusions from the demonstrator-A project are drawn. The two other documents provide more detailed information on the corresponding specific items.