High pT trigger electronics for a large orthogonal readout electromagnetic calorimeter

Abstract A trigger system has been designed and built to select events containing high p T electromagnetic showers detected in a large calorimeter with orthogonal readout. The electronics include analog adders with up to 123 inputs, pulse shapers with 20 ns integration time, 100 MHz flash ADCs and ECL loop-up tables. The total number of input channels is 3072 and the trigger decision is made in about 120 ns.