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ATLAS (A Toroidal LHC ApparatuS)〔 〕 is one of the seven particle detector experiments (ALICE, ATLAS, CMS, TOTEM, LHCb, LHCf and MoEDAL) constructed at the Large Hadron Collider (LHC), a particle accelerator at CERN (the European Organization for Nuclear Research) in Switzerland. The experiment is designed to take advantage of the unprecedented energy available at the LHC and observe phenomena that involve highly massive particles which were not observable using earlier lower-energy accelerators. It is hoped that it will shed light on new theories of particle physics beyond the Standard Model. ATLAS is 46 metres long, 25 metres in diameter, and weighs about 7,000 tonnes; it contains some 3000 km of cable.〔http://www.atlas.ch/fact-sheets-1-view.html〕 The experiment is a collaboration involving roughly 3,000 physicists from over 175 institutions in 38 countries.〔 (【引用サイトリンク】url=http://atlas.ch/what_is_atlas.html )〕 The project was led for the first 15 years by Peter Jenni and between 2009 and 2013 was headed by Fabiola Gianotti. Since 2013 it has been headed by David Charlton. It was one of the two LHC experiments involved in the discovery〔 〕 of a particle consistent with the Higgs boson in July 2012. ==History== The ''ATLAS collaboration'', the group of physicists who built and now run the detector, was formed in 1992 when the proposed EAGLE (''Experiment for Accurate Gamma, Lepton and Energy Measurements'') and ASCOT (''Apparatus with Super Conducting Toroids'') collaborations merged their efforts to build a single, general-purpose particle detector for the Large Hadron Collider.〔(【引用サイトリンク】title=ATLAS Collaboration records )〕 The design was a combination of the two previous experiments, and also benefitted from the detector research and development that had been done for the Superconducting Supercollider. The ATLAS experiment was proposed in its current form in 1994, and officially funded by the CERN member countries in 1995. Additional countries, universities, and laboratories joined in subsequent years, and further institutions and physicists continue to join the collaboration even today. Construction work began at individual institutions, with detector components then being shipped to CERN and assembled in the ATLAS experiment pit from 2003. Construction was completed in 2008 and the experiment detected its first single beam events on 10 September of that year.〔(【引用サイトリンク】title=First beam and first events in ATLAS )〕 Data taking was then interrupted for over a year due to an LHC magnet quench incident. On 23 November 2009, the first proton-proton collisions occurred at the LHC, at a relatively low injection energy of 450 GeV per beam. These collisions were successfully registered in ATLAS, which has been logging data ever since. All the while LHC energy has been increasing: 900 GeV per beam at the end of 2009, 3,500 GeV for the whole of 2010 and 2011, then 4,000 GeV per beam in 2012 and finally 6,500 GeV per beam after a Long Shutdown in 2013 and 2014. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「ATLAS experiment」の詳細全文を読む スポンサード リンク
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