# 5.4: Large Hadron Collider, LHC

**At Grade**Created by: CK-12

## Lesson Objectives

- Describe the brief history of the CERN facilities.
- Give an overview of the purpose of the experiments at the LHC.

## Overview

When particles move at relativistic speeds, their energies are large enough to generate new particles when colliding with other particles. Huge amounts of energy can also overcome the strong nuclear force holding particles together. This may allow scientists to see what’s inside the protons and neutrons. To achieve these high energies, a bigger collider needs to be built.

CERN is the French acronym for European Nuclear Research Centre. This collider is located at the foot of the Jura mountains straddling the border between France and Switzerland (CERN, 2009). CERN built its first synchrotron accelerator in the late 1950s. The first synchrotron gained notoriety in 1959. Since then several new colliders have been built on top of existing colliders at CERN. The new colliders either use the previously built colliders for pre-staging or the existing tunnels. The current LHC is no different. It uses the tunnels that were finished in 1989 for the LEP, Large Electron-Positron Collider. The LEP ceased running in November 2000 to make room for construction of the LHC (CERN Courier, 2001). The LHC is retrofitting the LEP’s tunnels with the most advanced superconducting magnets and updating its detectors to collect new data. There are currently six experiments requiring six different detectors at the LHC (CERN, 2009).

When Einstein came up with his theory of general relativity he could not foresee the practical applications of this theory today. But a hundred years later, the theory of general relativity is used to calculate your position on the planet using a GPS-enabled device, (TED, Patricia Burchat: *The Search for Dark Energy and Dark Matter*, 2008). The LHC is doing science for the sake of education to answer some of the big questions such as:

- What causes mass?
- What is dark matter?
- Are there more than three spatial dimensions?

The implications in science and technology of these answers is not yet known. But in a hundred years, it may have a profound effect on society (TED, Brian Cox: *An Inside Tour of the World's Biggest Supercollider*, 2008).

**ALICE: A L**arge **I**on **C**ollider **E**xperiment

- Collisions in this section will be \begin{align*}100,000\end{align*} hotter than the sun.
- Looking for the particle responsible for mass.
- Investigating of quarks can be freed from protons and neutrons (CERN–ALICE Collaboration).
- Size: \begin{align*}26 \;\mathrm{m} \end{align*} long, \begin{align*}16 \;\mathrm{m}\end{align*} high, \begin{align*}16 \;\mathrm{m}\end{align*} wide (CERN, 2008).
- Mass: \begin{align*}10,000\end{align*} tons (CERN, 2008).
- Look up “ALICE” on Google Earth to see its location.

**ATLAS: A** **T**oroidal **L**HC **A**pparatu**S**

- It is a general purpose detector.
- Looks at mass while searching for evidence of:
- the Higgs particle responsible for mass.
- dark matter.

- The ATLAS is the largest particle detector in the world (CERN–ATLAS Experiment 2008).
- Size: \begin{align*}46 \;\mathrm{m}\end{align*} long, \begin{align*}25 \;\mathrm{m}\end{align*} high, and \begin{align*}25 \;\mathrm{m}\end{align*} wide (CERN, 2008).
- Mass: \begin{align*}7000\end{align*} metric tons (CERN, 2008).
- Look up “ATLAS” on Google Earth to see its location.

**CMS:** **C**ompact **M**uon **S**olenoid

- It is a general purpose detector.
- Looks at mass while searching for evidence of:
- the Higgs particle responsible for mass.
- dark matter.

- Unlike the ATLAS it will look for this evidence using different techniques (CERN–CMS Outreach).
- It generates a magnetic field 100,000 times stronger than the Earth’s.
- Size: \begin{align*}21 \;\mathrm{m}\end{align*} long, \begin{align*}15 \;\mathrm{m}\end{align*} wide, and \begin{align*}15 \;\mathrm{m}\end{align*} high (CERN, 2008).
- Mass: \begin{align*}12,500\end{align*} metric tons (CERN, 2008).
- Look up “CMS” on Google Earth to see its location.

**LHCb:** **L**arge **H**adron **C**ollider **B**eauty

- Looking to answer the question of why is there so little antimatter in our region of the universe (CERN–LHCb Experiment, 2008).
- Size: \begin{align*}21 \;\mathrm{m}\end{align*} long, \begin{align*}10 \;\mathrm{m}\end{align*} high, and \begin{align*}13\;\mathrm{m}\end{align*} wide (CERN, 2008).
- Mass: \begin{align*}5600\end{align*} metric tons (CERN, 2008).

**TOTEM: TOT**al **E**lastic and Diffractive Cross Section **M**easurement

- Looks at the size of the particles and the beam’s luminosity.
- This will complement the CMS’s data and give some quality assurance.
- Size: \begin{align*}440 \;\mathrm{m}\end{align*} long, \begin{align*}5\;\mathrm{m}\end{align*} high, and \begin{align*}5\;\mathrm{m}\end{align*} wide (CERN, 2008).
- Mass: \begin{align*}20\end{align*} metric tons (CERN, 2008).

**LHCf:** **L**arge **H**adron **C**ollider **F**orward

- Produces cosmic rays under laboratory conditions to look at how cosmic rays interfere with our atmosphere.
- Two detectors.
- Size: \begin{align*}30\;\mathrm{cm}\end{align*} long, \begin{align*}80\;\mathrm{cm}\end{align*} high, and \begin{align*}10\;\mathrm{cm}\end{align*} wide.
- Mass: \begin{align*}40 \;\mathrm{kg}\end{align*} each.

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