page_title: CERN
section_title: Large Hadron Collider
hierarchical_section_title: CERN / Particle accelerators / Current complex / Large Hadron Collider
caption_attribution_description: English: Construction of one detector (called CMS ) of the new LHC at CERN
context_page_description: The European Organization for Nuclear Research, known as CERN, is a European research organization that operates the largest particle physics laboratory in the world. Established in 1954, the organization is based in a northwest suburb of Geneva on the Franco–Swiss border and has 23 member states. Israel is the only non-European country granted full membership. CERN is an official United Nations Observer.
  The acronym CERN is also used to refer to the laboratory, which in 2016 had 2,500 scientific, technical, and administrative staff members, and hosted about 12,000 users. In the same year, CERN generated 49 petabytes of data.
  CERN's main function is to provide the particle accelerators and other infrastructure needed for high-energy physics research – as a result, numerous experiments have been constructed at CERN through international collaborations. The main site at Meyrin hosts a large computing facility, which is primarily used to store and analyse data from experiments, as well as simulate events. Researchers need remote access to these facilities, so the lab has historically been a major wide area network hub. CERN is also the birthplace of the World Wide Web.
context_section_description: Many activities at CERN currently involve operating the Large Hadron Collider (LHC) and the experiments for it. The LHC represents a large-scale, worldwide scientific cooperation project.
  The LHC tunnel is located 100 metres underground, in the region between the Geneva International Airport and the nearby Jura mountains. The majority of its length is on the French side of the border. It uses the 27 km circumference circular tunnel previously occupied by the Large Electron–Positron Collider (LEP), which was shut down in November 2000. CERN's existing PS/SPS accelerator complexes are used to pre-accelerate protons and lead ions which are then injected into the LHC.
  Eight experiments (CMS, ATLAS, LHCb, MoEDAL, TOTEM, LHCf, FASER and ALICE) are located along the collider; each of them studies particle collisions from a different aspect, and with different technologies. Construction for these experiments required an extraordinary engineering effort. For example, a special crane was rented from Belgium to lower pieces of the CMS detector into its cavern, since each piece weighed nearly 2,000 tons. The first of the approximately 5,000 magnets necessary for construction was lowered down a special shaft at 13:00 GMT on 7 March 2005.
  The LHC has begun to generate vast quantities of data, which CERN streams to laboratories around the world for distributed processing (making use of a specialized grid infrastructure, the LHC Computing Grid). During April 2005, a trial successfully streamed 600 MB/s to seven different sites across the world.
  The initial particle beams were injected into the LHC August 2008. The first beam was circulated through the entire LHC on 10 September 2008, but the system failed 10 days later because of a faulty magnet connection, and it was stopped for repairs on 19 September 2008.
  The LHC resumed operation on 20 November 2009 by successfully circulating two beams, each with an energy of 3.5 teraelectronvolts (TeV). The challenge for the engineers was then to try to line up the two beams so that they smashed into each other. This is like "firing two needles across the Atlantic and getting them to hit each other" according to Steve Myers, director for accelerators and technology.
  On 30 March 2010, the LHC successfully collided two proton beams with 3.5 TeV of energy per proton, resulting in a 7 TeV collision energy. However, this was just the start of what was needed for the expected discovery of the Higgs boson. When the 7 TeV experimental period ended, the LHC revved to 8 TeV (4 TeV per proton) starting March 2012, and soon began particle collisions at that energy. In July 2012, CERN scientists announced the discovery of a new sub-atomic particle that was later confirmed to be the Higgs boson.
  In March 2013, CERN announced that the measurements performed on the newly found particle allowed it to conclude that this is a Higgs boson. In early 2013, the LHC was deactivated for a two-year maintenance period, to strengthen the electrical connections between magnets inside the accelerator and for other upgrades.
  On 5 April 2015, after two years of maintenance and consolidation, the LHC restarted for a second run. The first ramp to the record-breaking energy of 6.5 TeV was performed on 10 April 2015. In 2016, the design collision rate was exceeded for the first time. A second two-year period of shutdown begun at the end of 2018.
caption: Construction of the CMS detector for LHC at CERN
exif: {"Image Make": "Canon", "Image Model": "Canon PowerShot A300", "Image Orientation": "Horizontal (normal)", "Image XResolution": "180", "Image YResolution": "180", "Image ResolutionUnit": "Pixels/Inch", "Image DateTime": "2003:10:10 11:40:28", "Image YCbCrPositioning": "Centered", "Image ExifOffset": "186", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "180", "Thumbnail YResolution": "180", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "1678", "Thumbnail JPEGInterchangeFormatLength": "9354", "EXIF ExposureTime": "1/25", "EXIF FNumber": "18/5", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2003:10:10 11:40:28", "EXIF DateTimeDigitized": "2003:10:10 11:40:28", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "3", "EXIF ShutterSpeedValue": "149/32", "EXIF ApertureValue": "59/16", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "59/16", "EXIF MeteringMode": "Pattern", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "5", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "640", "EXIF ExifImageLength": "480", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "Interoperability RelatedImageWidth": "640", "Interoperability RelatedImageLength": "480", "EXIF InteroperabilityOffset": "1530", "EXIF FocalPlaneXResolution": "40000/13", "EXIF FocalPlaneYResolution": "40000/13", "EXIF FocalPlaneResolutionUnit": "2", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "1", "EXIF SceneCaptureType": "Standard"}