‘OK, I’ve finished my job now’

On 13 August 1989, the OPAL experiment saw the first Z particle at the Large Electron-Positron collider. By 20 September, the machine was ready for serious physics. It was a period of enormous satisfaction for the teams that had worked together to bring the project to fruition and for the project leader Emilio Picasso.

The Bulletin issue with the announcement of first collisions at LEP. The original issue is available from the CERN Library.

Appointed project leader in 1980, by the new director-general, Herwig Schopper, Picasso was well known in particular for his work on the g-2 experiments at CERN. These had involved a storage ring 40 m in circumference, but LEP was something on an entirely different scale and this was precisely what made Picasso take on the challenge. "Everything that is new is attractive," he says, an outlook that has guided his career from cosmic-ray studies with balloons, through bubble chambers and g-2.

His first task was to set up a management board with the best people available: Gérard Bachy on installation; Roy Billinge for the PS; Franco Bonaudi on experimental halls; Giorgio Brianti as head of accelerators; Bas de Raad for the SPS; Andrew Hutton on machine parameters; Henri Laporte for civil engineering; Günther Plass as deputy leader; Hans Peter Reinhard on vacuum; Lorenzo Resegotti for the magnets; and Wolfgang Schnell for the RF. Schopper joined in regularly, mainly only to observe. "I was like the conductor of an orchestra", Picasso recalls. "It was a good team, we all knew each other well and respected each other".

Part of the tunnel was ready for installation by 1987, when Jacques Chirac, then French prime minister, visited CERN with Swiss president Pierre Aubert. Asked to arrange an event for the visitors, Picasso proposed that they position the first magnet. Not surprisingly, Chirac asked when the machine would be ready. At the time, there was no definite date, so Picasso decided there and then, answering "14 July 1989 - the 200th anniversary of the storming of the Bastille." While Chirac responded "very good", Picasso’s colleagues were less impressed: "Is Emilio crazy? How will we be ready?" By July 1988, however, the first sector was completely installed and a test with beam by the LEP operations team led by Steve Myers proved that the machine was indeed well designed. A year later, Picasso’s prediction was confirmed, when the first beam went round the ring at 11 pm on 14 July 1989.

A month later there was great jubilation as the first collisions occurred. "For a long 10 minutes, Steve Myers and I didn’t know whether the beams were colliding or not", Picasso recalls, "and then Aldo Michelini, the OPAL spokesman, called: ‘We have the first Z0.’ It was a beautiful moment. Steve had done an excellent job – and I thought, OK, I’ve finished my job now."

Did you know?

Experiments at LEP

The LEP accelerator had four interaction points. The detectors were named: ALEPH, DELPHI, L3 and OPAL. The first collaboration to register the collisions was OPAL, followed by ALEPH and L3. The DELPHI collaboration saw the first collisions one day later because of a misadjusted magnet in the accelerator that prevented the particles from colliding at that interaction point.