Speaker
Dr.
Francesca Pastore
(Royal Holloway University of London (UK))
Description
The ATLAS trigger has been used very successfully for the online event
selection during the first run of the LHC between 2009-2013 at a
centre-of-mass energy between 900 GeV and 8 TeV. The trigger system
consists of a hardware Level-1 (L1) and a software based high-level
trigger (HLT) that reduces the event rate from the design
bunch-crossing rate of 40 MHz to an average recording rate of a few
hundred Hz.
We will briefly review the performance of the ATLAS trigger system
during the past data-taking period and point out the challenges for
the trigger system during the next LHC run in early 2015 with a
smaller bunch spacing, almost twice the centre-of-mass energy and
higher peak luminosity. We will show the ongoing improvements and
upgrades to the existing system that will ensure an even better
performing trigger system despite the harsher machine conditions. This
includes changes to the L1 calorimeter trigger, the introduction of a
new L1 topological trigger module, improvements in the L1 muon system
and the merging of the previously two-level HLT system into a single
event filter farm. In addition, we will give an overview of the
algorithmic improvements in the various HLT algorithms used to
identify leptons, hadrons and global event quantities like missing
transverse energy.
Primary authors
Dr.
Francesca Pastore
(Royal Holloway University of London (UK))
Dr.
Joerg Stelzer
(CERN)
