A schematic drawing of the ATLAS detector, the largest volume particle detector ever constructed (Credit: CERN)

The LHC is the world's largest particle accelerator. Its primary structure consists of a 27 kilometer ring of supercold magnets that speed particles through its circuit. Two beams travel at nearly the speed of light in opposite directions through the ring until they collide at one of four set locations corresponding to various particle detectors within LHC.

 

The LHC only operated for nine days last year before an electrical fault caused a huge helium leak resulting in massive damage to the collider. Repairs include replacing 53 magnets, placement of additional pressure relief valves, and an extensive network of new cable needed to enable a new early warning system attempting to prevent further damage from electrical problems.

The general layout of the LHC ring showing the location of several of the particle detectors (Credit: CERN)

The LHC is home to six major particle physics experiments. ATLAS and CMS are general purpose detectors designed to investigate a large range of particles including the Higgs boson and dark matter. ALICE is an ion detector designed to recreate conditions presents in the universe shortly after the Big Bang. The LHCb examines the differences between matter and antimatter. TOTEM is designed to measure the size of the proton and to monitor the luminosity of the LHC itself. Finally, the LHCf simulates cosmic rays in laboratory conditions.

 

According to current plans, the LHC will inject protons back into the LHC in September 2009 and generate its first collisions about a month later. It will operate throughout the winter without the usual planned maintenance period and ions will be injected into the system at some point in late 2009. Ion collisions such as those measured by ALICE may resume by late 2010 with full operation planned for some time in 2011. It is unclear exactly which experiments will resume at each point in the timeline.

 

TFOT has previously reported on the start of operations at the LHC and its subsequent shutdown because of the helium leak. In March 2008 TFOT reported on the ATLAS being finally assembled following our original convergence of the detector back in 2006. We have also reported on other innovative physics laboratories and equipment, including the National Ignition Facility at Lawrence Livermore National Laboratory, the Magnet Lab at Los Alamos National Laboratory, and NASA's Gamma-Ray Large Area Telescope (now called the Fermi Gamma-Ray Space Telescope).

 

You can read more about the Large Hadron Collider, its goals, its physical structure, and the various experiments and detectors on the CERN pages devoted to the LHC. More in-depth information is also available in the CERN LHC brochure (PDF).