The Large Hadron Collider

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.

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.

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.

The LHC accelerates two beams of atomic particles in opposite directions around the 27km collider. When the particle beams reach their maximum speed the LHC allows them to ‘collide’ at 4 points on their circular journey.

Thousands of new particles are produced when particles collide and detectors, placed around the collision points, allow scientists to identify these new particles by tracking their behaviour.

The detectors are able to follow the millions of collisions and new particles produced every second and identify the distinctive behaviour of interesting new particles from among the many thousands that are of little interest.

As the energy produced in the collisions increases researchers are able to peer deeper into the fundamental structure of the Universe and further back in its history. In these extreme conditions unknown atomic particles may appear.

The LHC project includes 111 nations in designing, building and testing equipment and software, participating in experiments and analysing data. It is a remarkably harmonious international collaboration in which the UK has a leading role. British scientists and engineers have prominent roles in construction, management and experimental teams and the UK makes a significant contribution to the LHC budget.

CERN has many opportunities for students, postdoctoral researchers, scientists and technical experts in a range of disciplines (links to Working @ CERN)

UK research groups involved in the LHC project.

Over the 13 year construction period (1994 to 2006 inclusive) the total UK contribution for the detectors, GriddPP (materials and staff effort) and collider was £511M. This includes the UK’s annual CERN subscription over this period. This is less than the price of one pint of beer per UK adult per year.

The total cost to the UK of participating in the LHC project will be £108M per year, including £82M per year as its national subscription to CERN’s on-going annual budget of approximately £455M. The subscription of member countries to the CERN budget is linked to their GDP. Non-member countries are also involved in, and contribute to, experiments.

The cost of the LHC project (machine and personnel) is £2.1bn, or £3.5bn if the infrastructure costs, incurred during the construction phase, and the costs of computing, GRID, early running etc are included. The cost of the LHC is mainly paid for by the 20 members of CERN, with significant contributions from the 6 observer nations.

There are two types of benefit that the LHC project produces for the UK. The less easily measured benefits are:

• new understanding of the physical world,
• training of world class scientists and engineers,
• maintenance of a vibrant, world class UK research base and,
• a leading role in a major international project.

More easily appreciated are the knowledge, expertise and technology that is spun off from the LHC and can be directly applied to development of new medical, industrial and consumer technologies.

The science of the LHC is far removed from everyday life, but the fact that the science is so extreme constantly pushes the boundaries of existing technical and engineering solutions. Simply building the LHC has generated new technology.

The LHC is not primarily about building a better world. Rather, it allows us to test theories and ideas about how the Universe works, its origins and evolution. The questions asked, and answers found, are so fundamental that the information from LHC experiments will only be applied many years in the future, if at all. However, this is an experiment and one of the surprises from the experiment may be new science that can be applied almost immediately.

The LHC is physically located in a circular 27km (16.5m) long tunnel under the Swiss/French border outside Geneva, but as an international project the LHC crosses continents and many international borders.

In the UK, engineers and scientists at 20 research sites are involved in designing and building equipment and analysing data. UK researchers are involved with all four of the main detectors and the GRID. British staff based at CERN have leading roles in managing and running the collider and detectors.