Trigger and DAQ

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Introduction

The ATLAS data acquisition system is well suited to carrying out the measurements during Pb+Pb running. In this section results on triggering on Pb+Pb collisions are presented.

• Left: Level-1 jet 0.4 × 0.4 ROI ET distributions in reconstructed PYTHIA jets embedded to HIJING Pb+Pb events for three centrality bins - the most central (dN/deta = 2700, b = 2 fm), semi-peripheral (dN/deta = 1700, b = 6 fm), and peripheral collisions (dN/deta = 460, b = 10 fm). The distribution shows a number of ROIs per event satisfying a given threshold (x-axis).Right: A fraction of saturated events for a given threshold on JET ROI E4×4 T (x-axis) in minimum bias Pb+Pb events.

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• Left: Level-1 EM ROI ET distributions in reconstructed PYTHIA jets embedded to HIJING Pb+Pb events for three centrality bins - the most central (dN/deta = 2700, b = 2 fm), semiperipheral (dN/deta = 1700, b = 6 fm), and peripheral collisions (dN/deta = 460, b = 10 fm). The distribution shows a number of ROIs per event satisfying a given threshold (x-axis). Right: The efficiency of the jet trigger with EM/Tau ROIs included for three different centrality bins.

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• Estimated number of jets per event in the ATLAS acceptance above a given ET in minimum-bias Pb+Pb collisions.(see text for details).

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• Level-1 U trigger efficiency as a function of U pT obtained using PYTHIA p+p events with forced U production merged into minimum bias Pb+Pb HIJING and using default p+p muon trigger thresholds. Magenta points show single muon trigger efficiency (any Level-1 single muon trigger fired), while red histogram shows di-muon trigger efficiency (two muons passing trigger thresholds). Error bars show statistical errors only.

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Major updates:
-- AdamTrzupek - 27-Nov-2009

Responsible: AdamTrzupek
Last reviewed by: Never reviewed