Since the Large hadron Collider started physics runs early this year, the plan has been to run to the end of 2011 in order to collect 1/fb of data at 7 TeV. After that the collider would shut down for over a year to upgrade the magnets before allowing it to run at its full 14 TeV. But the plans at CERN for the LHC have always been somewhat flexible. Now with Fermilab hoping to extend the running of the Tevatron in order to scoop the LHC to the discovery of the Higgs, CERN are fighting back with talk of an extension of the current run that might find the Higgs even sooner.
This year the commissioning of the LHC has run somewhat better than hoped. In July when they stepped up the beam intensity they found it easier than expected to get to the designed count of 115 billion protons per bunch circulating in the ring. This meant that they could reach their target luminosity of 100/μb/s without stretching other parameters to their potential limits. By time the proton runs came to an end for the year, they had reached twice that target and were already trying out procedures to go to higher luminosity next year. With so much optimism in the air they have recently been talking of increasing the energy to 8 TeV during 2011. Projections suggest that they may be able to collect between 2/fb and 7/fb at that energy if they can live up to expectations of run efficiency. This would make the discovery potential of next year’s run much better than anticipated and so the payoff for continuing the run is much better. With such considerations in mind the CERN directorate is now proposing to extend the run to two years instead of just one, taking them to the end of 2012 before the long shutdown.
It remains to be seen how this will affect the decision at Fermilab to continue their run. Although they have expressed a strong wish to continue, they can only do so if they can find an extra $150 million and it is not clear where that will come from. Even if the money arrives as a new budget, other experiments at Fermilab will be held back by the continued running of the Tevatron. Not everyone thinks this is the best way forward for the lab.
As a successful run of Heavy Ion collisions enters its last few days at the LHC, the beam commissioning teams are now preparing their cases for how to run the collider when it starts up next year. A meeting at Evian on the 7th-9th December will be used to go over the possibilities with final details to be hashed out at Chamonix in January. The LHC is then expected to restart proton physics in February.
Meanwhile there will be some conferences to present any physics results they have using the 40/pb of data collected so far such as the “LHC First data” conference in Michigan on 12th December. (This does make me wonder how many more times the words “LHC” and “First” can appear together in a title.) We should not expect new positive results unless the physics gods are unusually kind with their favours.
As the year comes to an end let’s take this opportunity to thank CERN for allowing us such an open public view of the workings of the accelerator. We also thank the physicists who work on the detectors for bringing us their initial results so quickly. We look forward to so much more next year and beyond.