Speaker
Yu Higuchi
(High Energy Accelerator Research Organization (JP))
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. During the next data-taking period starting in early 2015
(Run-2) the LHC will operate at a centre-of-mass energy of about 13
TeV resulting in roughly five times higher trigger rates.
We will review the upgrades to the ATLAS Trigger system that have been
implemented during the shutdown and that will allow us to cope with
these increased trigger rates while maintaining or even improving our
efficiency to select relevant physics processes. 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. At hand of a few examples, we will show the impressive
performance improvements in the HLT trigger algorithms used to
identify leptons, hadrons and global event quantities like missing
transverse energy. And finally, we will summarize the commissioning
status of the Trigger system in view of the imminent restart of
data-taking.
Primary author
Yu Higuchi
(High Energy Accelerator Research Organization (JP))
