CERN Accelerating science

ATLAS Note
Report number	ATLAS-CONF-2012-045
Title	Transverse energy fluctuations in Pb+Pb collisions at $\sqrt{s_{NN}}$=2.76 TeV with the ATLAS detector at the LHC
Corporate Author(s)	The ATLAS collaboration
Collaboration	ATLAS Collaboration
Imprint	16 Apr 2012. - 6 p.
Subject category	Detectors and Experimental Techniques
Accelerator/Facility, Experiment	CERN LHC ; ATLAS
Free keywords	Heavy Ion Collisions ; Underlying Event Fluctuations
Abstract	A study of calorimeter energy fluctuations in Pb+Pb collisions and their dependence on centrality is presented, using an integrated luminosity of 240 mb^{−1} of Pb+Pb collisions at √s_{NN} = 2.76 TeV collected by the ATLAS detector in 2010. The fluctuations are characterized by the per-event standard deviation of the distribution of energies in single ∆η × ∆φ = 0.1 × 0.1 calorimeter towers and in windows covering larger areas of up to 11 × 11 calorimeter towers. The event-averaged standard deviations are calculated in fine bins of Forward Calorimeter (FCal) total transverse energy (ΣET) which is a measure of the collision centrality. The dependence of the mean standard deviation on the window area is also evaluated as a function of FCal ΣET . The results of these fluctuation measurements are compared to an identical analysis applied to fully-simulated HIJING events, and good agreement is found.
Copyright/License	Preprint: (License: CC-BY-4.0)

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