ENABLE - A SYSTOLIC 2ND LEVEL TRIGGER PROCESSOR FOR TRACK FINDING ANDE PI DISCRIMINATION FOR ATLAS/LHC/

The Enable Machine is a systolic 2nd level trigger processor for the t ransition radiation detector (TRD) of ATLAS/LHC. It is developed withi n the EAST/RD-11 collaboration at CERN. The task of the processor is t o find electron tracks and to reject pion tracks according to the EAST benchmark algorithm in less than 10 mus. Track are identified by temp late matching in a (phi,z) region of interest (RoI) selected by a 1st level trigger. In the (phi,z) plane tracks of constant curvature are s traight lines. The relevant lines form mask templates. Track identific ation is done by histogramming the coincidences of the templates and t he RoI data for each possible track. The Enable Machine is an array pr ocessor that handles tracks of the same slope in parallel, and tracks of different slope in a pipeline. It is composed of two units, the Ena ble histogrammer unit and the Enable z/phi-board. The interface daught er board is equipped with a HIPPI-interface developed at JINR/-Dubna, and Xilinx 'corner turning' data converter chips. Enable uses programm able gate arrays (XILINX) for histogramming and synchronous SRAMs for pattern storage. With a clock rate of 40 MHz the trigger decision time is 6.5 mus and the latency 7.0 mus. The Enable machine is scalable in the RoI size as well as in the number of tracks processed. It can be adapted to different recognition tasks and detector setups. The protot ype of the Enable Machine has been tested in a beam time of the RD6 co llaboration at CERN in October 1993.