Commissioning ATLAS Trigger

TL;DR

This paper discusses the commissioning process of the ATLAS trigger system at the LHC, which is designed to efficiently select interesting events from high-rate proton-proton collisions while rejecting background noise.

Contribution

It provides an overview of the commissioning progress of the multi-level trigger system crucial for data collection at the LHC.

Findings

Successful initial commissioning of the hardware trigger system

Progress in calibrating and testing the software trigger levels

Achievement of target data reduction rates

Abstract

The ATLAS experiment at the Large Hadron Collider (LHC) will face the challenge of efficiently selecting interesting candidate events in $pp$ collisions at 14 TeV centre-of-mass energy, whilst rejecting the enormous number of background events. Therefore it is equipped with a three level trigger system. The first level is is hardware based and uses coarse granularity calorimeter information and fast readout muon chambers. The second and third level triggers, which are software based, will need to reduce the first level trigger output rate of ~ 75 kHz to ~ 200 Hz written out to mass storage. The progress in commissioning of this system will be reviewed in this paper.