About the US/LHC Project

The Large Hadron Collider at CERN near Geneva, Switzerland is opening new vistas on the deepest secrets of the universe, stretching the imagination with newly discovered forms of matter, forces of nature, and dimensions of space. This site provides general information about the Large Hadron Collider and detailed information about American participation in the LHC accelerator and experiments. U.S. LHC participation is supported by the US Department of Energy's Office of Science and the National Science Foundation.

A proton-proton collision event in the CMS experiment producing two high-energy photons (red towers). This is what we would expect to see from the decay of a Higgs boson but it is also consistent with background Standard Model physics processes. (Courtesy: CERN)

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Lead-Ion Collisions in the Large Hadron Collider

The following images below depict real and simulated collisions of lead ions in the LHC experiments. Additional photos, video and information are available at these links:

Lead-ion collision images from the ALICE experiment
Lead-ion collision images from the CMS experiment
Lead-ion collision images from the ATLAS experiment
CERN press releases announcing the switch to lead-ion beams and the first lead-ion collisions
Symmetry Breaking article on how lead-ion beams are made at the LHC
Animations of simulated lead-ion collisions at the LHC
Two-minute video introduction to the ALICE experiment


One of the first lead-ion collisions in the LHC as recorded by the ALICE detector on November 8, 2010. Image copyright CERN for the benefit of the ALICE Collaboration.	One of the first lead-ion collisions in the LHC as recorded by the ALICE detector on November 8, 2010. Image copyright CERN for the benefit of the ALICE Collaboration.	One of the first lead-ion collisions in the LHC as recorded by the ATLAS experiment on November 8, 2010. Copyright 2010 The ATLAS Experiment at CERN.
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One of the first lead-ion collisions in the LHC as recorded by the ATLAS experiment on November 8, 2010. Copyright 2010 The ATLAS Experiment at CERN.	One of the first lead-ion collisions in the LHC as recorded by the CMS experiment on November 8, 2010. Image copyright CERN for the benefit of the CMS Collaboration.	One of the first lead-ion collisions in the LHC as recorded by the CMS experiment on November 8, 2010. Image copyright CERN for the benefit of the CMS Collaboration.
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The first lead-ion collisions in the LHC as recorded by the ALICE detector on November 7, 2010. Information from only part of the ALICE detector is included in this image. Image copyright CERN for the benefit of the ALICE Collaboration.	Simulation of a lead-ion collision in the ALICE detector. Image copyright CERN for the benefit of the ALICE Collaboration.	Illustration of two colliding lead ions just after impact in the Large Hadron Collider. Image copyright CERN/Henning Weber.
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Simulated lead-ion collision event in the CMS detector in which jets of particles were produced. The jets can be seen at the top of the image. Image copyright CERN for the benefit of the CMS Collaboration.	A simulated lead-ion collision as seen by the ATLAS detector. This was a high-multiplicity collision, from which many particles were emitted. Copyright 2010 The ATLAS Experiment at CERN.	Three views of the same simulated collision of lead ions in the CMS detector. This collision produced a Z boson that decayed into two muons, shown by the yellow tracks. Image copyright CERN for the benefit of the CMS Collaboration.
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About the US/LHC Project

Lead-Ion Collisions in the Large Hadron Collider

Images are available for use following the rules of CERN Copyright.