First collisions

The OPAL experiment recorded the very first collision at about five past midnight on 13 August 1989 and the other three experiments followed soon after. The first fully-fledged physics run began on 20 September and continued for three months. During this time, the experiments each recorded around 30,000 Z particles, enough for the first data analysis to get under way.

By the time LEP was officially inaugurated on 13 November 1989, in the presence of some 1500 guests including heads of state and ministers from all of CERN’s Member States, the first results had already been announced – the experiments had confirmed that only three types of neutrinos exist, and hence only three generations of matter particles.