A flexible demonstrator system for the ATLAS level-1 calorimeter trigger

The proposed level-1 calorimeter trigger system for ATLAS relies upon several key technologies which we have been testing in a demonstrator programme. We describe here the final phase of this programme, which concentrates on crucial aspects of high-speed data transmission inherent in the trigger architecture while operating with signals from prototype ATLAS calorimeters. The 36-channel trigger demonstrator system has been designed to provide a flexible infrastructure for the study of alternative techniques of communication between the calorimeters and the trigger processor, including both analogue links and high-speed digital optical and electrical links operating at up to 1.6 Gbaud. Data fan-out at 160 Mbit/s between trigger processor modules using serialising Application Specific Integrated Circuits (ASICs) driving transmission-line backplanes is also evaluated. A programmable timing system re-synchronises all channels before pipeline processing by ASICs executing an electromagnetic cluster-finding algorithm. Some preliminary results are presented from the operation of this demonstrator system installed in the ATLAS test-beam at CERN.