The cool-down and commissioning of the LHC continues to progress well. Six of the eight sectors were at a nominal temperature of 1.9 K by the end of the first week of October, and the final two sectors, 3-4 and 6-7, were on course to be fully cold two weeks later. Teams are starting to power the magnets as each sector reaches 1.9 K, so the machine should be fully powered soon after the cool-down is completed.
The new layer of the quench detection system (QDS), installed in four sectors, is functioning well. In particular, the new software and hardware QDS components allowed teams to measure the resistance of all of the splices in sector 1-2 quickly and with unprecedented accuracy. All of the measured resistances showed small values and most are significantly below the original specifications. Teams were also able to test the new energy-extraction system that dumps the stored magnetic energy twice as quickly as previously. This provides better protection for the whole machine.
Preparations are thus continuing towards the planned restart, with the injection of the first bunches of protons into the machine scheduled for mid-November. The procedure will be to establish stable beam initially in each direction, clockwise and anticlockwise, just as with LEP 20 years ago (When LEP, CERN’s first big collider, saw beam). This will be followed by a short period of collisions at the injection energy of 450 GeV per beam. Commissioning will then begin on ramping the energy to 3.5 TeV, again working first with each beam in turn. After this, LHC physics will finally begin with collisions at this energy.
• CERN publishes regular updates on the LHC in its internal Bulletin, available at www.cern.ch/bulletin, as well as on its main website www.cern.ch and via Twitter and YouTube, at www.twitter.com/cern and www.youtube.com/cern respectively.
