Beam test of the ATLAS level-1 calorimeter trigger system
IEEE Nuclear Science Symposium Conference Record, Bd. 3, IEEE, 2004.
IEEE Nuclear Science Symposium Conference, Rome, Italy, Oktober 2004
The level-1 calorimeter trigger consists of a preprocessor (PP), a
cluster processor (CP), and a jet/energy-sum processor (JEP). The
CP and JEP receive digitised trigger-tower data from the preprocessor
and produce regions-of-interest (RoIs) and trigger multiplicities.
The latter are sent in real time to the central trigger processor
(CTP) where the level-1 decision is made. On receipt of a level-1
accept, readout driver modules (RODs) provide intermediate results
to the data acquisition (DAQ) system for monitoring and diagnostic
purposes. RoI information is sent to the RoI builder (RoIB) to help
reduce the amount of data required for the level-2 trigger. The level-1
calorimeter trigger system at the test beam consisted of 1 preprocessor
module, 1 cluster processor module, 1 jet/energy module and 2 common
merger modules. Calorimeter energies were successfully handled throughout
the chain and trigger objects sent to the CTP. Level-1 accepts were
successfully produced and used to drive the readout path. Online
diagnostics were made using 4 RODs. Energy histograms were plotted
and the integrity of data between the different modules was checked.
All ATLAS detectors in the test beam were able to build full events
based on triggers delivered by the calorimeter trigger system.