The pixel detector barrel is the last large piece of the CMS detector to be lowered into the cavern. 

A component known as a small wheel is the last large piece of the ATLAS detector to be lowered into the cavern. The ATLAS detector has the largest volume of any detector ever constructed.

After six and a half years of work, CERN leaders and dignitaries celebrate the completion of a second detector cavern. The CMS cavern is 53 x 27 x 24 metres. To make space for the enormous detector, 250,000 cubic metres of soil have been removed from the detector cavern and a second space that houses technical components.

The LHC forward collaboration proposes to build two small calorimeters near the ATLAS detector for high-energy cosmic ray research.

Read the LHCf letter of intent

After three years of work, the ATLAS detector cavern (35 x 55 x 40 metres) is fully excavated and completed. CERN officials and dignitaries celebrate the first new LHC cavern on 4 June 2003, complete with an alpinhorn player.

The Monopole and Exotics Detector at the LHC proposes to build a detector to search for highly ionizing particles and slow exotic decays at the LHC. The letter of intent marks the first official use of the name MoEDAL. It will be the LHC’s seventh detector.

Read the MoEDAL letter of intent

At the December session of the CERN council, representatives of the United States sign an agreement to contribute $531 million to the Large Hadron Collider (LHC) project. Martha Krebs, Director of the Office of Energy Research (DOE) and Bob Eisenstein, Assistant Director of Physical and Mathematical Science at the National Science Foundation sign on behalf of the US, and CERN Director-General Christopher Llewellyn Smith signs on behalf of the laboratory.

At the same meeting, the US is granted observer status at CERN.

The Total Cross Section, Elastic Scattering Diffraction Dissociation collaboration proposes to build a detector to measure the basic properties of proton-proton collisions at high energy. The letter of intent marks the first official use of the name TOTEM.

Read the TOTEM letter of intent

The CERN Council admits Japan as an observer state. Japan announces a financial contribution to the LHC. The Japanese Minister for Education, Sciences and Culture offers a Daruma doll to CERN’s Director-General. According to Japanese tradition, an eye is painted on the doll to mark the beginning of the LHC project and the second eye must be drawn at the time of its completion. Japan makes two other major financial contributions to the LHC project in 1996 and 1998.

The first prototype bending-magnet for the LHC reaches a field of 8.73 Tesla, which is higher than the 8.4 Tesla field at which the LHC will operate in 2012.

Superconducting magnets must be "trained" so that they can maintain the superconducting state necessary to achieve such high fields. Any abnormal termination of the superconducting state, which switches the magnet back to its normal, resistive state, is called a "quench."

LHC Director Lyn Evans receives a hand-written note as he sits in a Finance Committee meeting. It reads:

Message de J.P Goubier et R.Perin à L Evans
on a attaint 8,73 tesla
100 quench

They mean "sans quench" - a pun on the French word "cent" or "one hundred", which is pronounced the same as the word for "without".