Large hadron collider - Important Facts

The LHC

The Large Hadron Collider (LHC) is the most powerful particle accelerator ever built and is capable of pushing protons or Ions upto 99.9999991% of the speed of Light. The accelerator sits in a tunnel 175 metres underground at CERN, the European Organization for Nuclear Research, on the Franco-Swiss border near Geneva, Switzerland.

 It consists of a 27-kilometre ring of superconducting magnets with a number of accelerating structures that boost the energy of the particles along the way. 

Super conducting Magnets

• The LHC comprised of 9593 super magnets, which are 1,00,000 times more powerful than the gravitational pull.
•  These are made up of 36 twisted 15 mm strands. Each strand consists of 6000-9000 turns of single filaments of diameter 7 microns. The 27 km long LHC circuit demands 7,600 km of cable, which amounts Upto 2,70,000 km of strand(more than enough to circle the earth six times at the equator).

If the filaments were unraveled would stretch to sun and come back five times with enough left over to make 150 trips to the moon.

Temperature and Pressure

• Magnets are precooled to -193.2°(80K) using 10,080 tonnes of liquid nitrogen then filled with 120 tonnes of liquid helium to bring them down to -271.3°(1.9K).
• Each Proton posses 7 TeV of energy, when fully accelerated and 14 TeV at the time of collision. At this stage temperature reachs upto 1,00,000 times the temperature at the center of the sun i.e nearly equal to the temperature just after the 'Big- Bang'.
• To avoid collision with gas molecules, the accelerator is maintained at Ultra -high vacuum( approx 10,000 billions of atmospheric pressure).

How LHC Works ?

Basic layout of LHC at CERN complex

   The CERN accelerator complex is a succession of machines with increasingly higher energies. Each machine accelerates a beam of particles to a given energy before injecting the beam into the next machine in the chain. This next machine brings the beam to an even higher energy and so on. The LHC is the last element of this chain, in which the beams reach their highest energy. Inside the LHC, two particle beams travel in opposite directions, at close to the speed of light before they are made to collide. 

Goals of LHC

The Standard Model of particle physics – a theory developed in the early 1970s that describes the fundamental particles and their interactions – has precisely predicted a wide variety of phenomena and so far successfully explained almost all experimental results in particle physics.. But the Standard Model is incomplete. It leaves many questions open, which the LHC will help to answer.

• What is the origin of mass? The Standard Model does not explain the origins of mass, nor why some particles are very heavy while others have no mass at all. However, theorists Robert Brout, François Englert and Peter Higgs made a proposal that was to solve this problem. The Brout-Englert-Higgs mechanism gives a mass to particles when they interact with an invisible field, now called the “Higgs field”, which pervades the universe. Particles that interact intensely with the Higgs field are heavy, while those that have feeble interactions are light. In the late 1980s, physicists started the search for the Higgs boson, the particle associated with the Higgs field. In July 2012, CERN announced the discovery of the Higgs boson, which confirmed the Brout-Englert-Higgs mechanism. However, finding it is not the end of the story, and researchers have to study the Higgs boson in detail to measure its properties and pin down its rarer decays.
   
• Will we discover evidence for  Supersymmetry ?  The Standard Model does not offer a unified description of all the fundamental forces, as it remains difficult to construct a theory of gravity similar to those for the other forces. Supersymmetry – a theory that hypothesises the existence of more massive partners of the standard particles we know – could facilitate the unification of fundamental forces.
   
• What are dark matter and dark energy? The matter we know and that makes up all stars and galaxies only accounts for 4% of the content of the universe. The search is then still open for particles or phenomena responsible for dark matter (23%) and dark energy (73%).
   
• Why is there far more matter than antimatter in the universe?Matter and antimatter must have been produced in the same amounts at the time of the Big Bang, but from what we have observed so far, our Universe is made only of matter.
   
• How does the quark-gluon plasma give rise to the particles that constitute the matter of our Universe? For part of each year, the LHC provides collisions between lead ions, recreating conditions similar to those just after the Big Bang. When heavy ions collide at high energies they form for an instant the quark-gluon plasma, a “fireball” of hot and dense matter that can be studied by the experiments.

Detectors Used in LHC

There are seven experimentsinstalled at the LHC: ALICE, ATLAS,CMS, LHCb, LHCf, TOTEM andMoEDAL. They use detectors to analyse the myriad of particles produced by collisions in the accelerator. These experiments are run by collaborations of scientists from institutes all over the world. Each experiment is distinct, and characterized by its detectors.

Data flow from LHC

The CERN Data Centre stores more than 30 petabytes of data per year from the LHC experiments, enough to fill about 1.2 million Blu-ray discs. Over 100 petabytes of data are permanently archived, on tape and have been analysed by scientists all around the world with a global network of computers.

Power Consumption by the LHC

The total power consumption of the LHC (and experiments) is equivalent to 600 GWh per year, with a maximum of 650 GWh in 2012 when the LHC was running at 4 TeV. For Run 2, the estimated power consumption is 750 GWh per year.
The total CERN energy consumption is 1.3 TWh per year while the total electrical energy production in the world is around 20000 TWh, in the European Union 3400 TWh, in France around 500 TWh, and in Geneva canton 3 TWh.