LHC Report: Full data production mode

The LHC is accumulating as much data as possible for the experiments before the summer conferences. Performance is impressive, with 1380 bunches of around 1.5x10¹¹ protons per bunch giving a peak luminosity of 6.8 x10³³ cm^-2s^-1 and with integrated rates topping 20 pb^-1 an hour at the start of fill. 

As of today (13 June), the LHC has delivered more collisions in 2012 than it did in the whole of 2011. Not only that, the collisions have been at the higher energy of 4 TeV. In 2011, the LHC delivered an integrated luminosity of around 5.6 fb^-1 to both ATLAS and CMS. Now, just a few months after the machine began its 2012 run, these integrated luminosity levels have been past. Follow the LHC performance and statistics on the dedicated page.

The step-up in particle collision rates compared with 2011 is due to further reduction in the beam sizes at the interaction point, in conjunction with the use of tight collimator settings, the increase in energy to 4 TeV and the continued excellent beam quality from the injectors. The interplay of the tighter collimators and beam-beam effects has led to occasional beam instabilities. The effect is under scrutiny.

Operation in general is currently marked by some long, productive fills (one 23 hour fill gave 240 pb^-1) interspersed with periods of wrestling down technical problems from a variety of sources. The large distributed systems such as the quench protection and the cryogenics systems are performing remarkably well but there are inevitably issues. The effects of radiation to tunnel electronics appear to have been reduced following intensive work during the Christmas stop but nonetheless single event effects are still causing some problems. However, given its complexity, the LHC is enjoying remarkable availability. 

by Mike Lamont for the LHC Team