LHC Schedule

February 08, 2011

The LHC has just made a major announcement about its plan for the next several years. The various directors of the Large Hadron Collider and its experiments have just announced that the LHC will run in physics mode through the end of 2012 instead of only through 2011 as was originally planned. This schedule is a major change from the most recent plans in which the accelerator was to run only until the end of this year and then shut down for a year of repairs and upgrades. Now the plan is for the LHC to go through a nearly two year long shutdown starting at the end of 2012. This announcement comes on the heels of the announcement that the Tevatron, the 1 TeV particle collider at Fermilab in Illinois, will cease operations in September of 2011.

The plan is to continue to collide protons at a center-of-mass energy of 7 TeV until the end of 2012, which is the same energy that was used throughout 2010. Initially, there was some discussion of increasing the energy to 8 Tev (which is still short of the design energy of 14 TeV). However, to ensure stability and to avoid any glitches that may have come from an increase in energy (or any outright disasters similar to the September 2008 incident), an increase in energy, for now, is no longer a part of the plan.

This move significantly alters the physics prospects of the LHC over the next few years. The biggest question is how these changes effect the LHCs prospects of discovering the Higgs Boson. Many believed that the Tevatron would have had a good chance at finding the Higgs with high significance if allowed to run for a few more years. But the recent announcement of its cancellation means that the only hope for finding the elusive particle lies in Europe (there is a joke among physicists that Bosons can only be discovered in Europe and fermions are discovered in the US, which at least historically has seemingly been the case). Over the next two years it is estimated that the ATLAS detector will collect 5 Inverse femptobarns worth of data. At 7 TeV, this MAY be enough statistics to officially discover the Higgs (by having 5-sigma significance), or at least to have a good idea of its mass. However, inn order to maximize the chances of making discovery, analysts will have to become more aggressive in their strategies for seeking out the Higgs.

A move to 8 TeV would not simply be symbolic. The small increase in energy could mean a large increase in the amount of Higgs produced and could lead to much better statistics (depending on the Higgs mass). The decision to not increase the colliders energy dramatically effects the prospects for potential discoveries other than the Higgs. It essentially means that supersymmetry (if it exists) will not be discovered before 2015 or so.

I think the LHC is doing the right thing by extending this years upcoming run (to resume again in a month or so) by another year. It will reduce the chances of an accident and ensure that a lot of good data comes out of the machine as quickly as possible. It will hopefully (with luck and hard work) lead to an earlier discovery of the Higgs (there is no doubt that during the two year break after 2012, the data will be reprocessed and reanalyzed as much as possible to find any hints of new physics). And while it will delay some interesting physics, it will ensure that the machine is well understood and working well as safely and as quickly as possible.