Inside the Large Hadron Collider : photos from CERN

CERN began in the 1950s as the European Organization for Nuclear Research. Today it is also known as the European Laboratory for Particle Physics. It is one of the world's most prestigious research centres. Its business is fundamental physics - finding out what makes our Universe work, where it came from and where it is going.

CERN's accelerator complex is built around three principal inter-dependent accelerators. The oldest, the Proton Synchrotron (PS), was built in the 1950s and was briefly the world's highest energy accelerator. The Super Proton Synchrotron (SPS), built in the 1970s, was the scene of CERN's first Nobel prize in the 1980s. The Large Electron-Positron collider (LEP) came on stream in 1989. It was the Laboratory's flagship research machine until 2000. LEP was an enormous machine. Built in a circular underground tunnel, it was 27 kilometres around and weighed over 23 000 tonnes.

The Large Hadron Collider (LHC) is a gigantic scientific instrument near Geneva, where it spans the border between Switzerland and France about 100m underground. In technical terms it is a new accelerator inside the same tunnel as LEP and which provides six experiments with collisions. The experiments are called ATLAS, CMS, LHCb, ALICE, TOTEM and LHCf. Those are used by physicists to study the smallest known particles – the fundamental building blocks of all things. It will revolutionize our understanding, from the minuscule world deep within atoms to the vastness of the Universe.

Two beams of subatomic particles called "hadrons" – either protons or lead ions – travel in opposite directions inside the circular accelerator, gaining energy with every lap. Physicists 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 then analyse 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. 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 high 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.

CERN was founded in 1954 as one of Europe's first joint ventures. Since then it has become a shining example of international collaboration. From the original 12 signatories of the CERN convention membership has grown to 20 Member States. The Laboratory sits astride the Franco-Swiss border west of Geneva at the foot of the Jura mountains. Some 7000 scientists, over half the world's particle physicists, use CERN's facilities. They represent some 500 universities and over 80 nationalities.

The six experiments at the LHC are all run by international collaborations, bringing together scientists from institutes all over the world. Each experiment is distinct, characterised by its unique particle detector.

The two large experiments, ATLAS and CMS, are based on general-purpose detectors to analyse the myriad of particles produced by the collisions in the accelerator. They are designed to investigate the largest range of physics possible. Having two independently designed detectors is vital for cross-confirmation of any new discoveries made. Two medium-size experiments, ALICE and LHCb, have specialised detectors for analysing the LHC collisions in relation to specific phenomena. Two further experiments, TOTEM and LHCf, are much smaller in size. They are designed to focus on "forward particles" (protons or heavy ions). These are particles that just brush past each other as the beams collide, rather than meeting head-on.

The ATLAS, CMS, ALICE and LHCb detectors are installed in four huge underground caverns located around the ring of the LHC. The detectors used by the TOTEM experiment are positioned near the CMS detector, whereas those used by LHCf are near the ATLAS detector.

[Ref.] CERN homepage http://public.web.cern.ch/public/Welcome.html

[Ref.] CERN http://public.web.cern.ch/public/en/lhc/lhc-en.html

[Ref.] CERN http://public.web.cern.ch/public/en/lhc/LHCExperiments-en.html

[Ref.] photoshoot http://www.livescience.com/21041-large-hadron-collider-photos.html

[Ref.] photoshoot http://www.telegraph.co.uk/news/picturegalleries/worldnews/2688712/Scientists-at-CERN-have-achieved-high-power-collisions-of-sub-atomic-particles-in-the-Large-Hadron-Collider.html