Highlights from the history of the Large Hadron Collider at CERN, the European Organization for Nuclear Research, based in Geneva.

Early 1980s – Scientists discuss proposal for a new, giant physics research machine to be known as the Large Hadron Collider.

1983 – Groundbreaking ceremony for the Large Electron-Positron collider. LEP is the largest scientific instrument ever constructed. The tunnel built for it has a circumference of 17 miles (27 kilometers), larger than needed so it can later house the proposed Large Hadron Collider.

1989 – LEP starts up.

1991 – CERN's Council endorses proposed Large Hadron Collider.

1993 – The U.S. Congress cancels the Superconducting Super Collider – which was to have been the world's largest collider – after five years of construction in Texas costing $2 billion.

1997 – After agreeing to provide significant financial contributions to the LHC, the United States becomes an observer at CERN Council.

1998 – Civil engineering for the LHC gets under way, with parts manufactured around the world.

2000 – LEP is shut down after running for 11 years to make way for the LHC. First LHC parts from the United States arrive.

2001 – A computer grid project to connect tens of thousands of computers worldwide is launched to handle data from LHC.

2003-2008 – Installation of major LHC equipment in the tunnel.

Sept. 10, 2008 – Launch of LHC after an outlay of $10 billion.

Sept. 11 – Shutdown of LHC after a transformer fails.

Sept. 18 – LHC is recooled to near absolute zero after transformer is replaced.

Sept. 19 – Apparent electrical fault in a separate superconducting area causes a large leak of liquid helium into the tunnel. The LHC is shut down for at least two months so that its temperature can be raised to permit repairs.