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Chamonix: What The LHC Experiments Will Be Doing This Summer February 3, 2009

Posted by gordonwatts in LHC.

LHC_magnet[1] Wow – I didn’t realize how many meetings there were going on this week! In ATLAS there is the trigger workshop I’m attending in Beatenberg. I know of a Liquid Argon Calorimeter week going on in Marrakesh (lucky bastards!). The Chamonix meeting, however, is the one where everyone wishes they could be a fly on the wall at.

Every year for years and years (going back more than 20 years, I’m given to understand) the CERN accelerator folks decamp to Chamonix to discuss all things CERN accelerators (perhaps to do a bit of skiing to!?!?). CERN is large and quite active – with more than the LHC going on, so they have a lot to discuss! Of special interest, of course, is how they will manage the startup for the LHC.

The current date for startup is this summer — July. That is subject to change, of course, if they find a problem with the ongoing repairs. The news I’ve heard of the repairs has been quite smooth – though I’m not really plugged into the rumor mill. So perhaps that July date will stand – which would be great.

But there is a lot more to decide than the start up date. What energies will they try to run at? How many protons will they put in the machine: how intense will they make the beam? How fast will they ramp the energy and intensity up? Heck, how long will they experiment with single beams before they try colliding beams?

From the experiments point of view, the most important a few collisions (at least in my opinion). It almost doesn’t matter what energy they are at. Even just a few days would be a huge help to commission the detectors. We’ve taken 100’s of millions of cosmic rays now – we know a lot about the basic performance of a substantial fraction of the detector. But the trigger and timing ourselves to match the LHC’s collisions is hard! We all guess there is a lot of work there. And any data at all would be a huge help. The process is sort of like diminishing returns: the first dollop of data lets you get the big things right, the next the next most important things are tuned up, etc. And what is worse is those first fixes are usually the largest and require the most time – imagine if we’d had a few days of collisions last September. Wow – we’d be so much further along than we are today (or we know that we were so much further along if everything had worked)!

Of course everyone wants to do physics as well. There the experiments will probably push for higher energies – if the LHC will accumulate only a small amount of data those higher energies are required to give any competition at all to the Tevatron. Of course, the LHC may want to operate at lower energies to keep things safe.

We’ll see what they say…



1. Haryo - February 7, 2009

Hi Gordon,

The CERN Director General’s message to the CERN community on Friday evening CET described the results of the Chamonix workshop. By now you must have read it. Hope more detailed information (and probably official press release) will come soon.

2. gordonwatts - February 8, 2009

Yeah — I saw that. I was amazed that he wrote that so quickly — I don’t think the last DG would have. As you point out – there were no dates, but reading between the lines it sounds like colliding beams in the fall. I think there is some sort of talk scheduled for the 24th of Feb – and that one I hear will have actual dates that all of the CERN management has agreed to. So we’ll just have to sit tight for now – but that if true that is great that they see the end of these repairs.

3. LHC News « Life as a Physicist - July 3, 2009

[…] is eager for data. I’ve discussed what I think are some of the pressures on the accelerator division previously. This meeting is a continuing part of that […]

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