10 fascinating facts about the LHC

Fact 1) When the 27-km long circular tunnel was excavated, between Lake Geneva and the Jura mountain range, the two ends met up to within 1 cm.

Fact 2) Each of the 6000–9000 superconducting filaments of niobium–titanium in the cable produced for the LHC is about 0.007 mm thick, about 10 times thinner than a normal human hair. If you added all the filaments together they would stretch to the Sun and back six times with enough left over for about 150 trips to the Moon.

Fact 3) All protons accelerated at CERN are obtained from standard hydrogen. Although proton beams at the LHC are very intense, only 2 nanograms of hydrogen are accelerated each day. Therefore, it would take the LHC about 1 million years to accelerate 1 gram of hydrogen.

Fact 4) The central part of the LHC is the world’s largest fridge. At a temperature colder than deep outer space, it contains iron, steel and the all important superconducting coils.

Fact 5 ) The pressure in the beam pipes of the LHC is about like the atmosphere of the Moon. This is an ultrahigh vacuum.

Fact 6) Protons at the design energy in the LHC travel at 0.999999991 times the speed of light. Each proton goes round the 27 km ring more than 11000 times a second.

Fact 7) At full energy, each of the two proton beams in the LHC have a total energy equivalent to a 400 t train (like the French TGV) travelling at 150 km/h. This is enough energy to melt 500 kg of copper. However, because the beams are ultrarelativistic, the momentum (impact on a target) is the equivalent of a toy car pushed by a child.

Fact 8) ATLAS is the largest detector ever constructed for a particle collider, measuring 46 metres in length and 25 metres in diameter.

Fact 9) The CMS magnet system contains about 10000 t of iron, which is more iron than in the Eiffel Tower.

Fact 10) The data recorded by the big experiments at the LHC is enough to fill up to 88 000 1 TB hard disks per year.