Frequently asked questions

For general information about the Large Hadron Collider, see LHC: The Guide

How is the United States involved in LHC research?

The United States joined the LHC shortly after the CERN Council approved the project in 1994. US national laboratories designed and built many of the LHC focusing magnets and the supporting cryogenic systems. Today the US scientists continue to develop technology for future upgrades of the LHC, are heavily involved in all of the LHC experiments and hold many senior positions within the international collaborations.

 

When was the LHC constructed?

In December 1994, the CERN Council approved the construction of the LHC. Between 1996 and 1998, four experiments—ALICE, ATLAS, CMS and LHCb—received official approval, and construction work commenced on the four sites. The United States joined the project in 1995 and contributed to the design and construction of LHC magnets, the supporting infrastructure and all four experiments.

 

How much did it cost?

The cost for the LHC is about $5.23 billion and was split between CERN and many contributing countries, including the United States, Japan, India and other non-member states. The US LHC Accelerator Construction Project contributed $200 million to the construction project (funded by the US Department of Energy Office of Science). The United States also contributed $331 million toward the development, construction and operation of the ATLAS and CMS experiments.

 

When is the LHC running?

The first run of the LHC lasted from November 2009 through February 2013, after which it was shut down for two years for upgrades and repairs. The second run is spring 2015-2017.

 

What are scientists looking for at the LHC?

Scientists use the LHC as a tool to better understand the properties and origin of matter. They test theories and look for new physics and phenomena. This includes dark matter, supersymmetry, properties of the Higgs boson and new physics beyond the Standard Model. US scientists based at CERN and in the United States work with large international collaborations to study rare physical phenomena and hunt for new physics.

 

How do scientists study physical phenomena at the LHC?

When the high-energy particles accelerated by the LHC collide, they produce new particles. The higher the collision energy, the more types of particles produced. Huge detectors surround the collision points and give information to the scientists about the types and momenta of the particles. With this data scientists can reconstruct what occurred during the collision and look for new particles, physics and phenomena.

 

How many magnets does the LHC have?

The LHC uses more than 50 types of magnets to send particles along complex paths without their losing speed. Dipole magnets are used to bend the paths of the particles. There are 1,232 main dipoles, each 50 feet long and weighing in at 35 tonnes. Just prior to collision, quadrupole magnets "squeeze" the particles closer together to increase the chances of collisions. The LHC has 392 quadrupole magnets, each 16 to 23 feet long. The United States contributed to the construction of several quadrupole magnets, cryogenic systems and other supporting infrastructure. Today the United States continues to develop new magnet technology for particle accelerators such as the LHC.

 

How cold is the LHC when it is operation?

The LHC magnets are superconducting. When a current passes through them, they create a powerful magnetic field and have zero electric resistance. To remain in a superconducting state, the magnets must be kept at 1.9 Kelvin, which is just above absolute zero. The LHC magnets are cooled with liquid helium in a complex cryogenic system. Many cryogenic systems for the focusing magnets were designed and constructed by US scientists and engineers.

 

How much power does the LHC use when it is in operation?

At peak consumption, usually from May to mid-December, CERN uses about 200 megawatts of power, which is about a third of the amount of energy used to feed the nearby city of Geneva in Switzerland.

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