Then-director-general John Adams showed that he had in mind a big future for experiments at CERN, going beyond LEP. The minutes of that meeting are the CERN archivesÂ’ first documented mention of the Large Hadron Collider, the proton-proton machine that will start operating in 2007.
While considering the diameter of the 27-kilometer-long tunnel needed to house LEP, Adams wanted to ensure it would be large enough to simultaneously house a proton-proton collider. Having both types of colliders in the same tunnel would have allowed additional types of collisions, like protons on electrons, by making the beams from the two rings collide.
The idea of dual colliders persisted for some years, and an internal CERN document reporting on a March 1984 meeting showed a schematic drawing of how a proton-proton collider could sit above the LEP machine. Eventually, the idea of running both machines was dropped in favor of removing the LEP machine, which ran from 1989 until 2000, and building the LHC in its place.
