The LHC performance workshop in Chamonix is over and the summary talk gives the proposed running parameters for this year (to be rubber stamped by the directorship) As expected the beam energy for this year will be 4 TeV.
As it turned out they never did do those thermal tests to see if the splices were up to it, but they formed a new risk assessment based on the fact that there have been no beam induced quenches in 2011. This was attributed to the successful use of snubber resistors (in case you needed to know such details)
To decide on whether they should run with 25ns or stick with 50ns they took completion of the Higgs search as the priority criterion. They figure this will require precisely 13.3 /fb at 4TeV so that ATLAS and CMS have enough data independently. Using the predictions for luminosity that were reported on in December they find that at 50ns they would collect 16.5/fb while at 25ns they could only reach 11.5/fb, so obviously they must run at 50ns. I suspect that if they added error bars to some of those numbers the conclusion would not be so clear cut 🙂 . beta* will be 0.6m whereas the earlier luminosity estimates assumed beta* of 0.7m, never mind that this brings the estimate at 25ns up to 13.5 /fb, just enough to find the Higgs 🙂 . 50ns is the right decision anyway.
They also have an option to run for an extra 2 months before the long shutdown if that is needed to complete the search. Don’t be surprised if they do need it.