The ATLAS Level - 1 Calorimeter Trigger Pre - Processor

At the input to the calorimeter part of the Level-1 Trigger a Pre-Processor system performs the preprocessing of about 7200 analogue trigger-tower signals. The preprocessing includes digitisation, identi cation of the corresponding bunch-crossing in time (BCID), calibration of the transverse energy, rate monitoring, readout of raw trigger data, and high-speed data transmission to the following processors. The preprocessing of a large number of analogue signals requires a compact Pre-Processor system with fast hard-wired algorithms implemented in application-speci c integrated circuits (ASICs). In this paper we present the tasks of the Pre-Processor, measurement results, and advanced technologies used for the preprocessing of about 7200 analogue signals.