Detector Electronics Division ATLAS Level1 Calorimeter Trigger Processor

Detector & Electronics Division ATLAS Level-1 Calorimeter Trigger Processor Introduction The ATLAS Level-1 Trigger algorithms are carried out by a Calorimeter Trigger processor (electrons and photons, jets, taus, missing and total transverse energy) and a Muon Trigger processor (high transverse-momentum muons in barrel and end-caps). The results of these two processors are combined in the Central Trigger Processor (CTP) to produce the level-1 trigger. Technical Specification • The "real time" first-level trigger must reject 999 crossings out of 1000. • The first-level trigger must be active for each crossing every 25 nanosecs. • While the trigger is making its decision, detector data from all subsequent beam crossings must be retained in buffers on the detector. • Since these buffers are expensive they are kept as small as possible. In ATLAS it is set ATLAS Level-1 Calorimeter Trigger to 100 beam-crossings (2. 5 s) of which CPM, CMM, ROD + many ‘support’ modules such as the Timing, only about 1 s is available for the first. Can. Bus monitoring system were UK responsibility level trigger processor. • It also provides Region of Interest (Ro. I) Technical Achievements information to the Level-2 trigger system as well as data for monitoring and diagnostics Processing and moving large amount of data to the DAQ system at high rates requires a great deal of sophistication: • A custom-built pipeline processor operating at frequency of 40 MHz and multiples of it • High-speed serial links • 160 Mbit/s backplane data transfers • 1 -3 Million gate FPGAs performing trigger algorithms • High density and complex PCB designs. Testing Read-out Module This work as part of the ATLAS-Level-1 Calorimeter Trigger Collaboration from UK, Germany and Sweden For further information contact: Viraj Perera at v. perera@stfc. ac. uk