LHC - Large Hadron Collider

Tunnelling to the beginning of time

The Large Hadron Collider

The LHC (Large Hadron Collider) is an international project, in which the UK has a leading role. This site includes the latest news from the project, accessible explanations of how the LHC works, how it is funded, who works there and what benefits it brings us. You can access a wide range of resources for the public, journalists and teachers and students, there are also many links to other sources of information.

The LHC is asking some Big Questions about the universe we live in

How did our universe come to be the way it is?

The Universe started with a Big Bang – but we don’t fully understand how or why it developed the way it did. The LHC will let us see how matter behaved a tiny fraction of a second after the Big Bang. Researchers have some ideas of what to expect – but also expect the unexpected!

About the LHC

The LHC is an international research project based at CERN in Geneva, Switzerland, where scientists, engineers and support staff from 111 nations are combining state-of-the-art science and engineering in one of the largest scientific experiments ever conducted.

The LHC is the latest and most powerful in a series of particle accelerators that, over the last 70 years, have allowed us to penetrate deeper and deeper into the heart of matter and further and further back in time. The next steps in the journey will bring new knowledge about the beginning of our Universe and how it works, as the LHC recreates, on a microscale, conditions that existed billionths of a second after the birth of our Universe.

What is the LHC?

The LHC is exactly what its name suggests - a large collider of hadrons. Strictly, LHC refers to the collider; a machine that deserves to be labelled ‘large’, it not only weighs more than 38,000 tonnes, but runs for 27km (16.5m) in a circular tunnel 100 metres beneath the Swiss/French border at Geneva.

However, the collider is only one of three essential parts of the LHC project. The other two are:

• the detectors, which sit in 4 huge chambers at points around the LHC tunnel and
• the GRID, which is a global network of computers and software essential to processing the data recorded by LHC’s detectors.

The LHC’s 27km loop in a sense encircles the globe, because the LHC project is supported by an enormous international community of scientists and engineers. Working in multinational teams, at CERN and around the world, they are building and testing LHC equipment and software, participating in experiments and analysing data. The UK has a major role in leading the project and has scientists and engineers working on all the main experiments.

What will the LHC do?

The LHC will allow scientists to probe deeper into the heart of matter and further back in time than has been possible using previous colliders.

Researchers think that the Universe originated in the Big Bang (an unimaginably violent explosion) and since then the Universe has been cooling down and becoming less energetic. Very early in the cooling process the matter and forces that make up our world ‘condensed’ out of this ball of energy.

The LHC will produce tiny patches of very high energy by colliding together atomic particles that are travelling at very high speed. The more energy produced in the collisions the further back we can look towards the very high energies that existed early in the evolution of the Universe. Collisions in the LHC will have up to 7x the energy of those produced in previous machines; recreating energies and conditions that existed billionths of a second after the start of the Big Bang.

The results from the LHC are not completely predictable as the experiments are testing ideas that are at the frontiers of our knowledge and understanding. Researchers expect to confirm predictions made on the basis of what we know from previous experiments and theories. However, part of the excitement of the LHC project is that it may uncover new facts about matter and the origins of the Universe.

One of the most interesting theories the LHC will test was put forward by the UK physicist Professor Peter Higgs and others. The different types of fundamental particle that make up matter have very different masses, while the particles that make up light (photons) have no mass at all. Peter’s theory is one explanation of why this is so and the LHC will allow us to test the theory. More of the Big Questions about the universe that the LHC may help us answer can be found here.

Latest News from the LHC

The 10th September 2008 is LHCstart up date .

Everything is now ready for the first injection of proton beams into the LHC on the 10th September 2008.

This major milestone in the LHC project will be covered live by international broadcasters. UK media organisations will be at CERN and at a simultaneous media event in London.

CERN will webcast the startup (the link is on the CERN "first beam" page).

BBC Radio 4 will devote a day of programming to the LHC, including covering first injection of beams live on the Today programme. See the BBC website for programming, background etc.

In the weeks preceeding the start up, this web page and the CERN and STFCwebsites will carry information on the plans for coverage of the event.

Press Release announcing start up date.

Dr Tara Shears talks about some of the scientific questions that the LHC project will help us answer, on the www.labreporter.com website.

You can try your hand at running the LHC and interpreting collisions on oursimulator at www.particledetectives.net.

Proton beams have already been injected into the first metres of the LHC, to test the injection process, but the first attempt to circulate beams all the way around the LHC will be on the official start up day. If everything proceeds according to plan the beam will circulate all the way around the 27 km long LHC. Over the following months the LHC scientists and engineers will commission the LHC, running beams at higher energy with the intention of beginning collisions, using relatively low energy (5TeV) beams, towards the end of 2008.

The extensive preparations for the start of LHC experiments have included exhaustive safety assessments, including the potential risk of creating new particles, black holes etc. The latest risk assessment is available here.

FAQs

I have heard that the LHC will recreate the Big Bang, does that mean it might create another Universe and if so what will happen to our Universe?

People sometimes refer to recreating the Big Bang, but this is misleading. What they actually mean is:

• recreating the conditions and energies that existed shortly after the start of the Big Bang, not the moment at which the Big Bang started,
• recreating conditions on a microscale, not on the same scale as the original Big Bang and,
• recreating energies that are continually being produced naturally (by high energy cosmic rays hitting the earth’s atmosphere) but at will and inside sophisticated detectors that track what is happening.

No Big Bang – so no possibility of creating a new Universe.

How much does the LHC cost and who pays?

The direct total LHC project cost is £2.6bn, made up of:

• the collider (£2.1bn),
• the detectors (£575m).

The total cost is shared mainly by CERN's 20 Member States, with significant contributions from the six observer nations.

UK’s direct contribution to the LHC is £34m per year, or less than the cost of a pint of beer per adult in the UK per year:

The UK pays £70m per year as our annual subscription to CERN.

The LHC project involves 111 nations in designing, building and testing equipment and software, participating in experiments and analysing data. The degree of involvement varies between countries, with some able to contribute more financial and human resource than others.

CERN stands for 'Conseil Européen pour la Recherche Nucléaire' (or European Council for Nuclear Research); does that mean that CERN is studying nuclear power and nuclear weapons?

At the time that CERN was established (1952 – 1954) physics research was exploring the inside of the atom, hence the word ‘nuclear’ in its title. CERN has never been involved in research on nuclear power or nuclear weapons, but has done much to increase our understanding of the fundamental structure of the atom.

The title CERN is actually an historical remnant. It comes from the name of the council that was founded to establish a European organisation for world-class physics research. The Council was dissolved once the new organisation (the European Organization for Nuclear Research) was formed, but the name CERN remained.

Why is the LHC underground? Is it because it is doing secret experiments that scientists want to hide away?

The LHC has been built in a tunnel originally constructed for a previous collider (LEP – the Large Electron Positron collider). This was the most economic solution to building both LEP and the LHC. It was cheaper to build an underground tunnel than acquire the equivalent land above ground. Putting the machine underground also greatly reduces the environmental impact of the LHC and associated activities.

The rock surrounding the LHC is a natural shield that reduces the amount of natural radiation that reaches the LHC and this reduces interference with the detectors. Vice versa, radiation produced when the LHC is running is safely shielded by 50 – 100 metres of rock.

Can the work at CERN be used to build more deadly weapons?

Unlikely for two main reasons. Firstly, CERN and the scientists and engineers working there have no interest in weapons research. They are trying to understand how the world works, not how to destroy it.

Secondly, the high energy particle beams produced at the LHC require a huge machine (27km long, weighing more than 38,000 tonnes – half the weight of an aircraft carrier), consuming 120MW of power and needing 91 tonnes of supercold liquid helium). The beams themselves have a lot of energy (the equivalent of a Eurostar train travelling at top speed) but they can only be maintained in a vacuum, if released into the atmosphere they would immediately interact with atoms in the air and dissipate their energy in a very short distance.

Are the high energies produced by the LHC dangerous and what happens if something goes wrong?

The LHC does produce very high energies, but these energy levels are restricted to tiny volumes inside the detectors. Many high energy particles, from collisions, are produced every second, but the detectors are designed to track and stop all particles (except neutrinos) as capturing all the energy from collisions is essential to identifying what particles have been produced. Very little of the energy from collisions is able to escape from the detectors.

The main danger from these energy levels is to the LHC machine itself. The beam of particles has the energy of a Eurostar train travelling at full speed and should something happen to destabilise the particle beam there is a real danger that all of that energy will be deflected into the wall of the beam pipe and the magnets of the LHC, causing a great deal of damage. The LHC has several automatic safety systems in place that monitor all the critical parts of the LHC. Should anything unexpected happen (power or magnet failure for example) the beam is automatically ‘dumped’ by being squirted into a blind tunnel where its energy is safely dissipated. This all happens in milliseconds – the beam, which is travelling at 11,000 circuits of the LHC per second, will complete less than 3 circuits before the dump is complete.