Large Hadron Collider (LHC)

 Large Hadron Collider

    The large Hadron Collider is a massive particle accelerator used by physicists to study the smallest known particles. Two beams of subatomic particles protons or lead ions will travel in opposite directions colliding the two beams head-on at very high energy. Some people are afraid that it will create strange matter which turns everything it touches into strange matter meaning everything, miniature big bangs.

 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.

  LHC 'Big Questions'

 

1) 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.

 

2) How much did 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.The UK pays ~£95m 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.

3) 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.

4) 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.

5) 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.

6) 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.