Today is scheduled as the end of proton physics at the Large Hadron Collider and the last few fills are circulating this morning. The integrated luminosity recorded this year will end at about 5.2/fb each for CMS and ATLAS, 1.1/fb for LHCb and 5/pb for ALICE. For the remainder of this year they will return to heavy ion physics until the winter shutdown.
The good news this year has been the high luminosity achieved with peaks at 3.65/nb/s. This compares with the expectations of 0.288/nb/s estimated before the 2011 run began. The higher luminosity has been made possible by pushing beam parameters (number of bunches, bunch intensity, emittance, beta*) to give better than expected performance. The not so good news is that out of 230 days that were available for physics runs only 55 (24%) were spent in stable beams. This was due to a barrage of technical difficulties including problems with RF, Vacuum, cryogenics, power stability, UFOs, SEUs and more. There were times when everything ran much more smoothly and the time in stable beams was then twice the average. The reality is that the Large Hadron Collider pushes a number of technologies far beyond anything attempted before and nothing on such scales can be expected to run smoothly first time out. The remarkable amount of data collected this year is testament to the competence and dedication of the teams of engineers and physicists in the operation groups.
After the heavy ion runs they will start looking towards next year. There will be a workshop at Evian in mid December to review the year and prepare for 2012. Mike Lamont, the LHC Machine Coordinator will be providing a less technical overview for the John Adams Lecture on 18th November.