The last few months have seen several important objectives of the CMS LS1 programme completed, giving increasing confidence in the final outcome. In particular, the Tracker is running cold, the Phase 1 beam-pipe has passed acceptance tests at CERN and, at the + z end of the experiment, the new YE4 disk is complete and installation is finished for the revised first muon station and new 4th muon station. All the teams involved have made extraordinary efforts to complete their tasks, sometimes under substantial schedule pressure. Although less visible a milestone than these other achievements, the almost un-noticed closure last week of the YB-1 wheel over the re-installed thermal shields of the –z end solenoid vacuum tank actually marked a subtle, but important change of course in the critical path of work in UXC. This was the first element to be definitively locked into position ready for the 2015 run, and it is quite possible that it will not be accessed again until Long Shutdown 3, in a decade’s time. All teams are aware of this and are taking care to identify any remaining tasks, or repairs, missing items or forgotten tools, before making these definitive closures.

Some delays have accumulated due to unforeseen tasks, such as installation of humidity control within the insulated cooling bundles of the Tracker, integration issues affecting the new CO2 cooling distribution for the Phase 1 pixel tracker and replacement of leaking hoses and fittings in the vacuum tank thermal shields. However, proposals for recovering lost time, discussed at the recent Technical Coordination LS1 workshop, are already being acted upon and should ensure that CMS is nevertheless ready for first beam in early 2015. Thus, at the –z end, the 4th muon station CSC’s have been installed before the second YE4 is constructed (based on good experience with the first YE4) and the final pump-down of the beam-pipe has been postponed until January, maintaining the option of re-opening the experiment, should serious faults be discovered during the first days of operation with magnetic field in early November. Right now, the configuration is the mirror image of that in the second part of 2013, aimed at finishing the remaining YE4 and muon stations at the – end, whilst completing maintenance of the +z end barrel wheels in parallel. Once that’s finished, the path will lead steadily towards beam-pipe installation and the critical bake-out of the beam-pipe during August, around which the whole 2014 schedule pivots.