The ATLAS experiment

ATLAS Collaboration publishes Letter of Intent

1 October 1992

The A Toroidal LHC ApparatuS (ATLAS) collaboration proposed to build a general-purpose detector at the LHC, an idea born in the 1980s. The letter of intent was submitted to the LHC Experiments Committee, which marked the first official use of the name ATLAS.

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Submission of Technical Proposal

15 December 1994

ATLAS submitted the technical proposal of the experiment to the LHC Experiments Committee. Approval to proceed with technical design reports was granted in early 1996, followed by the submission of the first report on 15 December of the same year. A long series of technical design reports have been submitted since then. In July 1997, the Committee approved the construction of the ATLAS detector. Teams all over the world built detector components and worked on final technical developments.

 

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ATLAS cavern inaugurated

4 June 2003

After five years of innovative and ingenious civil engineering, the ATLAS detector cavern (35 x 55 x 40 metres) was fully excavated. ATLAS, CERN officials, and political authorities, including the President of the Swiss Confederation Pascal Couchepin, celebrated the inauguration of the first cavern on the Large Hadron Collider on 4 June 2003. Installation of the detector in the cavern began soon after. 

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World’s largest superconducting magnet switches on

20 November 2006

The ATLAS Barrel Toroid, a characteristic component of the detector, then the largest superconducting magnet ever built, was switched on for the first time. It works together with the two Endcap Toroids and central Solenoid magnet systems to bend the paths of charged particles produced in collisions at the LHC, enabling important properties to be measured.

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First LHC collisions at 7 TeV

30 March 2010

(Image: Martin Aleksa, Lyndon Evans, Fabiola Gianotti and Peter Jenni toast running at 7 TeV)

After initial lower energy collision physics from November 2009 onwards, ATLAS records collisions at 7 TeV centre-of-mass energy for the first time.

Particle physicists around the world anticipate a rich harvest of new physics as the LHC begins its first long run at an energy three and a half times higher than previously achieved at a particle accelerator.

“It’s a great day to be a particle physicist,” says CERN Director-General Rolf Heuer. “A lot of people have waited a long time for this moment, but their patience and dedication is starting to pay dividends.”

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ATLAS and CMS observe a particle consistent with the Higgs boson

4 July 2012

On 4 July 2012, as a curtain raiser to the year’s major particle physics conference, ICHEP 2012 in Melbourne, the ATLAS and CMS experiments present their latest preliminary results in the search for the long-sought Higgs particle. Both experiments have observed a new particle in the mass region around 125-126 GeV. 

The next step is to determine the precise nature of the particle and its significance for our understanding of the universe. Are its properties as expected for the long-sought Higgs boson, the final missing ingredient in the Standard Model of particle physics? Or is it something more exotic? The Standard Model describes the fundamental particles from which we, and every visible thing in the universe, are made, and the forces acting between them. All the matter that we can see, however, appears to be no more than about 4% of the total. A more exotic version of the Higgs particle could be a bridge to understanding the 96% of the universe that remains obscure.

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Preparing for increase in total energy towards 14 TeV

1 February 2013

(Image: The ATLAS pixel detector is reinserted into the experiment after upgrade work)

In February 2013, the LHC and its experiments, including ATLAS, began its first Long Shutdown for maintenance and first upgrades to prepare for higher luminosity operations. By the end of 2013, ATLAS had produced almost 300 publications. 

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Data-taking to continue until 2035

1 January 2014

The LHC will be upgraded to 14 TeV collision energy. The first major upgrade is Phase I, scheduled for 2018, and Phase 2 in 2022. The experiments will continue taking data until 2035. By then ATLAS expects to have collected 100 times more data than they had at the beginning of Long Shutdown 1.

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