Abstract
The transverse energy () in Pb-Pb collisions at 2.76 TeV nucleon-nucleon center-of-mass energy () has been measured over a broad range of pseudorapidity () and collision centrality by using the CMS detector at the LHC. The transverse energy density per unit pseudorapidity () increases faster with collision energy than the charged particle multiplicity. This implies that the mean energy per particle is increasing with collision energy. At all pseudorapidities, the transverse energy per participating nucleon increases with the centrality of the collision. The ratio of transverse energy per unit pseudorapidity in peripheral to central collisions varies significantly as the pseudorapidity increases from to . For the 5% most central collisions, the energy density per unit volume is estimated to be about at a time of after the collision. This is about 100 times larger than normal nuclear matter density and a factor of 2.6 times higher than the energy density reported at at the Relativistic Heavy Ion Collider.
- Received 12 May 2012
DOI:https://doi.org/10.1103/PhysRevLett.109.152303
This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
© 2012 CERN, for the CMS Collaboration
Viewpoint
New Measurements of the Most Perfect Liquid
Published 8 October 2012
Producing quark-gluon matter from higher-energy nuclear collisions will give insight into its fluidlike properties.
See more in Physics