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)

Home > About the LHC > Experiments > TOTEM

What is TOTEM?

Part of the TOTEM detector. Image © CERN

The TOTEM (Total Cross Section, Elastic Scattering and Diffraction Dissociation) experiment measures the effective size of the proton—its so-called "cross-section"—to an unprecedented precision.

Modest in size, TOTEM has been installed near the point where protons collide in the center of the CMS detector. It uses silicon sensors installed in the LHC tunnel approximately 650 feet away from CMS.

The TOTEM collaboration comprises some 100 members from 10 universities and laboratories in seven countries, including US physicists from Case Western Reserve University.

Read more about the Science of TOTEM to learn about what this experiment studies.