Carlo Rubbia delayed his departure to the Lisbon High Energy Physics Conference by a day so that on 10 July he was able to announce that the UA1 detector had seen its first proton–antiproton collisions. It implied that the machine physicists had to push their collision rates still higher, and this they did in style in the second historic proton–antiproton run from April to July 1983. However, the event was not a clean example of a particle–antiparticle pair and it was only after three more events had turned up in the course of the month that CERN went public, announcing the discovery of the Z to the press on 1 June.