Implementation and Performance of the High-Level Trigger electron and photon selection for the ATLAS experiment at the LHC

The ATLAS three-tier trigger system faces the challenge to reduce the incoming rate of 40 MHz to â¼ 200 Hz. It consists of hardware based Level-1, and a software based High-Level Trigger (HLT). In this paper an overview of the selection algorithms for electrons and photons will be given as well as the expected performance. The electron and photon trigger menu and the strategy for the initial phase of LHC exploitation

The ATLAS Trigger/DAQ Authorlist, version 1.0

This is a reference document giving the ATLAS Trigger/DAQ author list, version 1.0 of 20 Nov 2008

The ATLAS Trigger/DAQ Authorlist, version 2.0

This is the ATLAS Trigger/DAQ Authorlist, version 2.0, 31 July 200

The ATLAS trigger - high-level trigger commissioning and operation during early data taking

The ATLAS experiment is one of the two general-purpose experiments due to start operation soon at the Large Hadron Collider (LHC). The LHC will collide protons at a centre of mass energy of 14~TeV, with a bunch-crossing rate of 40~MHz. The ATLAS three-level trigger will reduce this input rate to match the foreseen offline storage capability of 100-200~Hz. This paper gives an overview of the ATLAS High Level Trigger focusing on the system design and its innovative features. We then present the ATLAS trigger strategy for the initial phase of LHC exploitation. Finally, we report on the valuable experience acquired through in-situ commissioning of the system where simulated events were used to exercise the trigger chain. In particular we show critical quantities such as event processing times, measured in a large-scale HLT farm using a complex trigger menu

The ATLAS Trigger/DAQ Authorlist, version 3.1

This is the ATLAS Trigger/DAQ Authorlist, version 3.1, 17 September 200

The ATLAS Trigger/DAQ Authorlist, version 3.0

This is the ATLAS Trigger/DAQ Authorlist, version 3.0, 11 September 200