3.5 TeV: Patience pays dividends

In my message this week, I’d like to congratulate the LHC team on accelerating two beams to 3.5 TeV in the early hours of this morning. The timing could not have been better. Coming during a week of CERN Council meetings, it allowed us to show delegates the great progress we’re making.

The occasion also gave us the opportunity to set out again the prudent step-by-step approach that we’re taking to get the LHC up and running, and it was refreshing to hear one member of the Scientific Policy Committee declare on Monday that we should never forget that the LHC is not a turnkey machine.With the progress the LHC is making, that simple fact would be easy to overlook. The figures coming back from this first run are already quite remarkable. In Week 10, the LHC’s availability for the operators was over 65%: it usually takes a new accelerator years to reach that level. And over the last few weeks, operation of the LHC at 450 GeV has become routinely reproducible, which is again a feat that usually takes a new machine much longer to achieve.

All this augurs very well for the future, but we must not lose sight of the fact that the LHC is new, and it wasn’t bought off the shelf. It is a state-of-the-art prototype that is pushing the limits of technology across a wide range of disciplines, and as such it needs to be treated with the greatest respect. We have recovered well from the incident of 19 September 2008, and are now poised on the threshold of a new era of discovery. But the legacy of that incident will be with us for some time to come.

As we approached 3.5 TeV, we encountered a phenomenon linked to the machine protection systems that has obliged us to increase the ramp time from 15 minutes to around 75. This will only be a temporary solution while we correct this effect. With a machine like the LHC, this is typical of the kind of challenge we face through the switch-on phase, and we must be prepared for others.

Traditionally, CERN has operated its accelerators on an annual cycle, running for seven to eight months with a four to five month shutdown each year. With the LHC, things are different. Being a cryogenic machine operating at very low temperature, the LHC takes about a month to bring up to room temperature and another month to cool down. A four-month shutdown as part of an annual cycle no longer makes sense for such a machine. That’s why we decided in Chamonix to move to a longer cycle with longer periods of operation accompanied by longer shutdown periods when needed. Only when the repairs and consolidation are complete after the LHC’s next shutdown will we be fully able to consign 19 September 2008 to the history books.

In the meantime, we can take satisfaction in what we have achieved to date, while reminding ourselves, as that SPC delegate advised, that we are breaking new ground technologically as well as scientifically. Our stepwise approach, agreed by the management, the machine and the experiments, is the only sensible way to proceed. It takes time. But, as we’ve seen this week, patience pays dividends.


by Rolf Heuer