CERN70: Switching on the Large Hadron Collider

I had been asked to lead the LHC project in 1993, before it had even been approved. I guess I was naïve to have accepted!
Lyn Evans

Lyn Evans came to CERN in 1969 as a research fellow, before becoming a staff member in 1971. He was LHC Project Leader from 1994.

"I'd never wanted a public switch-on for the LHC, but there'd been a big build-up and there was this nonsense about blowing up the Universe. It was at a time when the web and social media were sufficiently well established for news to travel widely, and there was enormous concern. So, we had no choice, we couldn't just get beam and then announce it. But there were risks to being so public: the night before the switch-on, the cryogenic system stopped working and we only recovered it in the morning of 10 September 2008, just before we could start up the beam!

Nobody could have imagined it would work so quickly. For LEP, in 1989, it took two months to commission. For the LHC, it took just two hours!

The screen showed one spot when the beam entered the LHC and it was supposed to show a second spot when the beam made a full turn. I thought it hadn't worked, because there was a delay, but then we saw the two spots, even three spots as it had gone around twice. The room erupted in applause, it felt like a football match!

The LHC project had spanned the mandates of four Director-Generals and each of them was perfectly timed. Llewellyn Smith 's diplomacy helped to get the project approved. Maiani's physics background helped to convince a reluctant physics community to stop LEP, to make room for the LHC. Aymar's engineering background meant he fully understood the reality of the manufacturing issues, and he saw the project through to the end. When the physics programme began in 2010, Heuer was in charge.

I had been asked to lead the LHC project in 1993, before it had even been approved. I guess I was naïve to have accepted, but I'd been division leader already and, alongside other tasks, I'd worked on initial designs since the 1980s, when the first ideas for the LHC came up after a meeting in Lausanne.

It was a 15-year construction project, with plenty of challenges along the way. Four suppliers went bankrupt. We had warehouses all over the Pays de Gex with components for magnet building, to have a buffer in our supply chain. The project was based on a just-in-time installation, but a one-year delay in the cryogenic line meant that we had hundreds of magnets above ground, waiting to be installed, in car parks, exposed to the elements. Every time I took an aeroplane, I'd look out of the window and see a sea of blue dipoles!

Before the switch-on, we had taken seven sectors to full energy, but there hadn't been time to do the eighth. There were 10 000 high-current joints between the magnets, and we knew that the weak point could be the interconnections. We'd even calculated the risk of failure and had a probability of 10^-4. But bear in mind that 10^-4 x 10 000 = 1 and, indeed, on 19 September 2008, nine days after the switch-on, we saw where the failure was. It happened around lunchtime; I was with Human Resources discussing contracts and got a call. I immediately went to the CERN Control Centre (CCC) and saw all the screens were red! One joint had failed and the relief valves weren't big enough for the overpressure. It knocked about 50 magnets out of alignment. We had spares to make the repairs, but it took about a year.

Looking back now, I'd say that the incident was a blessing for the LHC experiments. It gave them extra time to use cosmic rays to calibrate their detectors and make simulations, so when we switched the LHC back on in 2010, we were able to ramp up much faster.

What the incident showed me is that there's something about the people at CERN: when the going gets tough, the tough get going. Everyone sprang into action and used ingenuity to make it work. It's like that at CERN, we quickly solve issues as they arise."

Video extract of the highlights of the first LHC beam on 10 September 2008. (Video: CERN)

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Read more about the day the world switched on to particle physics and how the LHC is now defying expectations by rivalling lepton colliders for precision in the CERN Courier.

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