Large Hadron Collider facts for kids

Map of the Large Hadron Collider at CERN

The Large Hadron Collider (LHC) is the biggest and most powerful particle accelerator in the world. It was built by CERN, which is the European Organization for Nuclear Research.

The LHC is a giant circular tunnel built deep underground. It is about 17 miles (27 kilometers) long. The tunnel is located between 50 and 175 meters below the surface. It crosses the border between Switzerland and France.

About 10,000 scientists and engineers from over 100 countries helped build the LHC. It cost around 10.4 billion Swiss francs (about $10 billion). Today, it is the largest and most complex research facility for experiments in the world.

What the LHC Does

The LHC studies tiny particles by making them crash into each other. The name "Hadron Collider" tells us that it crashes hadrons. A hadron is a type of particle made of even smaller parts called quarks. These quarks are held together by a very strong force.

Examples of hadrons are protons and neutrons. The LHC mainly crashes protons together in its experiments. Protons are parts of atoms that have a positive electrical charge.

How Protons Collide

The LHC speeds up these protons inside the tunnel. They get very close to the speed of light. Different groups of protons are sent in opposite directions. When they crash, they create conditions similar to the early universe.

Scientists use these crashes to study elementary particles. They also learn how these particles interact. The LHC has already taught us a lot about quantum physics. Researchers hope to learn more about the structure of space and time. The observations help us understand what the universe was like just after the Big Bang.

Making and Guiding Particles

To get the protons, the LHC starts with Hydrogen atoms. A hydrogen atom has one proton and one electron. The LHC removes the electron from the hydrogen atom. This leaves only the proton, which now has a positive charge.

The Super-Cold Tunnel

These hydrogen protons are then guided through the circular tunnel. Giant electromagnets keep them on track. For these magnets to be super strong, the tunnel must be extremely cold. Liquid helium cools the inside of the tunnel. It is kept at a temperature just above absolute zero. This is colder than outer space!

When the protons hit each other, their energy turns into many different particles. This process follows Einstein's famous equation, E=mc². This means energy can turn into mass, and mass can turn into energy.

Detecting the Collisions

At the crash sites, there are four layers of special detectors. The explosion from the collision passes through each layer. Each detector records a different part of the reaction.

These sensitive detectors track all the new particles created. By carefully looking at the data, scientists can study what particles are made of. They also learn how particles interact. Very high energy is needed to create some particles. The LHC's powerful collisions provide this energy.

The LHC's Main Parts

The LHC has three main parts:

• The particle accelerator (the tunnel itself)
• The four detectors
• The Grid

The accelerator makes the particles crash. But you can't see the results directly. The detectors turn the crash information into useful data. This data is then sent to the Grid.

The LHC Grid

The Grid is a huge network of computers. Researchers use it to understand the data from the detectors. It includes 170 locations in 36 different countries. These locations are filled with many regular desktop computers. All these computers are connected. Together, they act like one giant supercomputer. The LHC's Grid is thought to be the most powerful supercomputer ever built. These computers share their processing power and data storage space.

The Grid is very powerful. However, it can only process about one percent of the data it gets from the detectors. This limit has led to ideas for creating quantum computers. These new computers could use what the LHC has taught us about quantum mechanics to become even faster.

Discovering the Higgs Boson

Scientists recently used the LHC to find the Higgs boson. A boson is an elementary particle that carries force. This is different from fermions, which make up matter. The Higgs boson helps explain why particles have mass.

For a long time, scientists didn't know why some particles had mass and others didn't. For example, photons (light particles) don't have mass. The LHC's discovery of the Higgs boson proved that the Higgs field exists.

The Higgs Field

The Higgs field is an invisible field that is everywhere in the universe. When particles move through this field, they gain mass. The Higgs boson was the last particle predicted by the Standard Model of particle physics. Its discovery helps scientists confirm that the Standard Model is correct. It also helps us understand what the universe is made of.

Is the LHC Dangerous?

Some people worry that the LHC could create a black hole. They think this could be very dangerous. But there are two main reasons not to worry:

• First, the LHC does nothing that cosmic rays don't do every day. Cosmic rays hit Earth all the time, and they don't create black holes.
• Second, even if the LHC did make black holes, they would be incredibly tiny. The smaller a black hole is, the shorter its life. Very tiny black holes would quickly disappear and turn into energy before they could harm anyone.

History of the LHC

The LHC was first turned on on September 10, 2008. However, it didn't work right away. A cooling system broke, which was important for the magnets that guide the charged particles. This caused part of the facility to collapse.

Because of a planned winter shutdown, it wasn't used again until November 2009. While it was being fixed, scientists used another accelerator called the Tevatron to try and find the Higgs Boson.

When the LHC restarted in November 2009, it set a new speed record. It accelerated protons to 1.18 TeV (teraelectronvolt). A teraelectronvolt is a trillion electronvolts. On March 30, 2010, the LHC created a collision at 3.5 TeV.

Images for kids

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  Superconducting quadrupole electromagnets are used to direct the beams to four intersection points, where interactions between accelerated protons will take place.

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  The LHC protons originate from the small red hydrogen tank.

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  CMS detector for LHC

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  Seminar on the physics of LHC by John Iliopoulos (2009).

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  A section of the LHC

See also

In Spanish: Gran colisionador de hadrones para niños