20 years ago: first collisions (at LEP)

It’s been 20 years since the first electron positron collision at LEP, and I have to confess to a little self-indulgence in my message this week. Back then I was a member of the OPAL collaboration, the first to see collisions at LEP just before midnight on 13 August 1989 and almost exactly one month after the first circulating beam. It was a historic moment, and the atmosphere in the OPAL control room, 100 metres underground, was one of anticipation and excitement. We reported back to the LEP control room, champagne duly arrived, and over the next few hours, all the experiments were recording data. The pilot run was as smooth as it could be, and within weeks we were announcing new physics.

It’s interesting to contrast the start-up of LEP with that of the LHC. With the benefit of hindsight, LEP seems to have got going without a hitch, and indeed it was a smooth start. We circulated beam on 14 July, much to the joy of one of our host states, and it was just a month before the magic words ‘Colliding stable beams’ could be read on the monitors around the lab.

The reality, of course, is somewhat more complex. LEP was a much simpler machine than the LHC, especially at the beginning before the superconducting accelerating cavities were introduced. And there was a great deal of work behind that image of serenity. Back then, of course, the world was less interested in accelerator start-ups than it is today.

Beam diagnostics have also come a long way since 1989, and what was taking the LEP operations team days to do was being accomplished in just hours last September at the LHC. To get circulating beams in both directions on day one was a fantastic achievement for the machine operators, and to capture them and achieve stable circulating beams in just a few days was unprecedented.

Of course, what happened next is well known, and we’re still recovering from it. We are emerging stronger, and the LHC is a better machine than it was a year ago. Switching on a new accelerator is always a difficult task, and sometimes lessons are learned the hard way. That’s certainly true for the LHC, but one thing that last year’s short run has told us is that when we get the LHC running this November, we can expect it to run beautifully.

Rolf Heuer