Status of the ATLAS Level-1 Central Trigger and Muon Barrel Trigger and First Results from Cosmic-Ray Data

The ATLAS detector at CERN's Large Hadron Collider (LHC) will be exposed to proton-proton collisions from beams crossing at 40~MHz. A three-level trigger system will select potentially interesting events in order to reduce the read-out rate to about 200 Hz. The first trigger level is implemented in custom-built electronics and makes an initial fast selection based on detector data of coarse granularity. It has to reduce the rate by a factor of $10^4$ to less than 100~kHz. The other two consecutive trigger levels are in software and run on PC farms. We present an overview of the first-level central trigger and the muon barrel trigger system and report on the current installation status. Moreover, we show analysis results of cosmic-ray data recorded in situ at the ATLAS experimental site with final or close-to-final hardware

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 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 1.0

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