A second collider in the CERN LEP tunnel for pp (pp) and ep physics in the multitev energy range

The LEP collider at present under construction at CERN will provide e
⁹
e
⁹
collisions in four large detectors, initially at a centre of mass energy of 110 GeV to be gradually increased to ˜ 200 GeV by means of superconducting r.f. cavities. First beam is planned for the end of 1988. The tunnel has a circumference of ˜ 27 km and can house a second collider on top of the present one, designated as Large Hadron Collider (LHC)1 (Figs. 1 and 2).