Speaker
Martin Wessels
(Heidelberg University, KIP)
Description
The ATLAS Level-1 Calorimeter Trigger is one of the main elements
of the first stage of event selection for the ATLAS experiment at
the LHC. The input stage consists of a mixed analogue/digital
component taking trigger sums from the ATLAS calorimeters. This
stage determines the energies sent to the algorithmic trigger
logic. The complete processing chain is performed in a digital,
pipelined system, where programmable algorithms are performed in
parallel with a fixed latency of 2us. The real-time output consists
of counts of high-pt physics objects (jets, electron/photon
and tau candidates) and global energy triggers.
While the trigger system has been operational from time of the
very first LHC data, the final tuning of timing and calibration
had to wait for the higher luminosity proton-proton collision
data delivered by LHC in 2010. Many configurable parameters had
to be optimized in order to obtain the ultimate performance of
system in terms of bunch-crossing identification and energy
resolution. The behaviour of the system was also studied in
detail to understand unusual signals, and improve their response.
An analysis of the current status of the calorimeter trigger
hardware will be presented, along with the methods used to achieve
these results via increasingly precise calibrations.
Primary author
Martin Wessels
(Heidelberg University, KIP)
