Hadron Collider

Some 1,232 bending magnets keep the beams on their circular path, while an additional 392 focusing magnets are used to keep the beams focused, in order to maximize the chances of interaction between the particles in the four intersection points, where the two beams will cross. In total, over 1,600 superconducting magnets are installed, with most weighing over 27 tonnes.

Approximately 96 tonnes of liquid helium is needed to keep the magnets at the operating temperature (1.9K), making the LHC the largest cryogenic facility in the world at liquid helium temperature.
Once or twice a day, as the protons are accelerated from 450 GeV to 7 TeV, the field of the superconducting bending magnets will be increased from 0.54 T to 8.3 T.


Superconducting quadrupole electromagnets are used to direct the beams to four intersection points where interactions between protons will take place.

The protons will each have an energy of 7 TeV, giving a total collision energy of 14 TeV. At this energy the protons have a gamma factor of about 7,500 and move at about 99.999999% of light speed.

It will take less than 90 microseconds for a proton to travel once around the main ring (a speed of about 11,000 revolutions per second). Rather than continuous beams, the protons will be bunched together, into 2,808 bunches, so that interactions between the two beams will take place at discrete intervals never shorter than 25 ns apart.When the collider is first commissioned, it will be operated with fewer bunches, to give a bunch crossing interval of 75 ns. The number of bunches will later be increased to give a final bunch crossing interval of 25 ns.
Prior to being injected into the main accelerator, the particles are prepared by a series of systems that successively increase their energy.

The first system is the linear accelerator Linac 2 generating 50 MeV protons, which feeds the Proton Synchrotron Booster (PSB). There the protons are accelerated to 1.4 GeV and injected into the Proton Synchrotron (PS), where they are accelerated to 26 GeV.

Finally the Super Proton Synchrotron (SPS) is used to increase their energy to 450 GeV before they are at last injected (over a period of 20 minutes) into the main ring, where proton bunches are accumulated, accelerated (over a period of 20 minutes) to their peak 7 TeV energy, and finally stored for many hours (10 to 24) while collisions occur at the four intersection points.


The Large Hadron Collider's (LHC) CMS detectors being installed.

The LHC will also be used to collide lead (Pb) nuclei with a collision energy of 1,150 TeV. The other three, (LHCb, TOTEM, and LHCf), are smaller and more specialized.
Detectors
BBC quotes about LHC CMS detectors:

Purpose
When activated, it is theorized that the collider will produce the elusive Higgs boson.The verification of the existence of the Higgs boson would be a significant step in the search for a Grand Unified Theory, which seeks to unify three of the four known fundamental forces: electromagnetism, the strong nuclear force and the weak nuclear force, leaving out only gravity. In addition to the Higgs boson, other theorized particles, models and states might be produced, and for some searches are planned, including supersymmetric particles, compositeness (technicolor),extra dimensions, strangelets,micro black holes and magnetic monopoles


A Feynman diagram of one way the Higgs boson may be produced at the LHC.

Here, two quarks each emit a W or Z boson which combine to make a neutral Higgs.

Research


A simulated event in the CMS detector, featuring the appearance of the Higgs boson.

When in operation, about seven thousand scientists from eighty countries will have access to the LHC. The way around the diminishing returns is to upgrade the experiment, either in energy or in luminosity.

A luminosity upgrade of the LHC, called the Super LHC, has been proposed, to be made after ten years of LHC operation. The optimal path for the LHC luminosity upgrade includes an increase in the beam current (i.e., the number of protons in the beams) and the modification of the two high luminosity interaction regions, ATLAS and CMS.This will require an upgrade of the full pre-injector system, the needed changes in the Super Proton Synchrotron being the most expensive.
Cost
The total cost of the project is anticipated to be between €3.2 to €6.4 billion. The construction of LHC was approved in 1995 with a budget of 2.6 billion Swiss francs (€1.6 billion), with another 210 million francs (€140 million) towards the cost of the experiments. In part this was due to faulty parts lent to CERN by fellow laboratories Argonne National Laboratory or Fermilab).
Computing resources
The LHC Computing Grid is being constructed to handle the massive amounts of data produced by the Large Hadron Collider.

It incorporates both private fibre optic cable links and existing high-speed portions of the public Internet, to get data from CERN to academic institutions around the world.
The distributed computing project LHC@home was started to support the construction and calibration of the LHC. Under nominal operating conditions (2,808 bunches per beam, 1.15×1011 protons per bunch), the beam pipes contain 1.0×10-9 grams of hydrogen, which, in standard conditions for temperature and pressure, would fill the volume of one grain of fine sand.
Construction accidents and delays
On 25 October 2005, a technician was killed in the LHC tunnel when a crane load was accidentally dropped. On 27 March 2007 a cryogenic magnet support broke during a pressure test involving one of the LHC's inner triplet (focusing quadrupole) magnet assemblies, provided by Fermilab and KEK.

Fermilab director Pier Oddone stated "In this case we are dumbfounded that we missed some very simple balance of forces". Details are available in a statement from Fermilab, with which CERN is in agreement. Repairing the broken magnet and reinforcing the eight identical assemblies used by LHC delayed the startup date, then planned for November 2007, by several weeks.
In popular culture
The Large Hadron Collider has been featured in a number of novels, including Flashforward by Robert J.