Speaker
Description
The ATLAS experiment records about 1 kHz of physics collisions, starting from an LHC design bunch crossing rate of 40 MHz. To reduce the large background rate while maintaining a high selection efficiency for rare and Beyond-the-Standard-Model physics events, a two-level trigger system is used.
Events are selected based on physics signatures, such as the presence
of energetic leptons, photons, jets or large missing energy. A Trigger Menu is the compilation of about 2,000 individual triggers, specifying the selection algorithms to be used during data taking and the rate and bandwidth a given trigger is allocated. Trigger menus also take into consideration the instantaneous luminosity and limitations from the detector readout and offline processing farm. For Run-2, the ATLAS trigger has been enhanced to be able to handle higher instantaneous luminosities (up to 2.0x10^{34}cm^{-2}s^{-1}) and to ensure the selection robustness against higher average multiple interactions per bunch crossing.
In this presentation we discuss several aspects of the trigger menu design, such as physics goals, detector calibration, and constraints on rate, bandwidth, and CPU. We give an overview of the updated 2E34 Trigger Menu and the online system that is used to monitor the trigger performance in real time.
