The Large Hadron Collider

The LHC required forefront high precision engineering to design and build an accelerator to collide two beams each the thickness of a fraction of a human hair at speeds within a fraction of a percent of the speed of light. In order to maintain the required precision during operation even the effects of the moon and of hydrostatic pressure from Lake Geneva have to be taken into account.

During operation enormous energies are stored in the magnets but because the magnets are superconducting unlike a toaster the very high currents do not produce resistive heating. If the temperature of a magnet rises just a few tenths of a degree Kelvin the magnet becomes resistive and catastrophic failure can result because of heating. Sophisticated circuits are installed to remove the stored energy and prevent an accident. The failure of this safety mechanism resulted in the accident of Septeber 19th 2008 resulting in a years delay of the operation of the LHC. New safety systems have required the development of techniques to measure resistances of nano ohms (0.000000001).

For a full time line history of the LHC with images http://lhc-milestones.web.cern.ch/LHC-Milestones/year2005-en.html

Our understanding of the Universe is about to change...

The Large Hadron Collider (LHC) is a gigantic scientific instrument near Geneva, where it spans the border between Switzerland and France about 100 m underground. It is a particle accelerator used by physicists to study the smallest known particles – the fundamental building blocks of all things. It will revolutionize our understanding, from the miniscule world deep within atoms to the vastness of the Universe.

Two beams of subatomic particles called 'hadrons' – either protons or lead ions – will travel in opposite directions inside the circular accelerator, gaining energy with every lap. Physicists will use the LHC to recreate the conditions just after the Big Bang, by colliding the two beams head-on at very high energy. Teams of physicists from around the world will analyze the particles created in the collisions using special detectors in a number of experiments dedicated to the LHC.

There are many theories as to what will result from these collisions, but what's for sure is that a brave new world of physics will emerge from the new accelerator, as knowledge in particle physics goes on to describe the workings of the Universe. For decades, the Standard Model of particle physics has served physicists well as a means of understanding the fundamental laws of Nature, but it does not tell the whole story. Only experimental data using the higher energies reached by the LHC can push knowledge forward, challenging those who seek confirmation of established knowledge, and those who dare to dream beyond the paradigm.

Facts and figures

The largest machine in the world...

The precise circumference of the LHC accelerator is 26 659 m, with a total of 9300 magnets inside. Not only is the LHC the world’s largest particle accelerator, just one-eighth of its cryogenic distribution system would qualify as the world’s largest fridge. All the magnets will be pre‑cooled to -193.2°C (80 K) using 10 080 tonnes of liquid nitrogen, before they are filled with nearly 60 tonnes of liquid helium to bring them down to -271.3°C (1.9 K).

The LHC is located near Geneva Switzerland and is partly in Switzerland and partly in France. In the distance one can see the Swiss Alps and Mont Blanc. The LHC is 18 miles in circumference and will contain counter rotating beams of protons which will collide at a total enegy of 14 TeV. To provide the protons a a complex series of smaller accelerators is required.

The fastest racetrack on the planet...

At full power, trillions of protons will race around the LHC accelerator ring 11 245 times a second, travelling at 99.99% the speed of light. Two beams of protons will each travel at a maximum energy of 7 TeV (tera-electronvolt), corresponding to head-to-head collisions of 14 TeV. Altogether some 600 million collisions will take place every second.

The emptiest space in the Solar System...

To avoid colliding with gas molecules inside the accelerator, the beams of particles travel in an ultra-high vacuum – a cavity as empty as interplanetary space. The internal pressure of the LHC is 10^-13 atm, ten times less than the pressure on the Moon!

The hottest spots in the galaxy, but even colder than outer space...

The LHC is a machine of extreme hot and cold. When two beams of protons collide, they will generate temperatures more than 100 000 times hotter than the heart of the Sun, concentrated within a minuscule space. By contrast, the 'cryogenic distribution system', which circulates superfluid helium around the accelerator ring, keeps the LHC at a super cool temperature of -271.3°C (1.9 K) – even colder than outer space!

The biggest and most sophisticated detectors ever built...

To sample and record the results of up to 600 million proton collisions per second, physicists and engineers have built gargantuan devices that measure particles with micron precision. The LHC's detectors have sophisticated electronic trigger systems that precisely measure the passage time of a particle to accuracies in the region of a few billionths of a second. The trigger system also registers the location of the particles to millionths of a meter. This incredibly quick and precise response is essential for ensuring that the particle recorded in successive layers of a detector is one and the same.

The most powerful supercomputer system in the world...

The data recorded by each of the big experiments at the LHC will fill around 100 000 dual layer DVDs every year. To allow the thousands of scientists scattered around the globe to collaborate on the analysis over the next 15 years (the estimated lifetime of the LHC), tens of thousands of computers located around the world are being harnessed in a distributed computing network called the Grid.

The ultimate guide to the LHC

More information, facts and figures on the LHC can be found in CERN FAQ – LHC the guide.

Source:
http://public.web.cern.ch/Public/en/LHC/Facts-en.html