CMS Bulletin

RUN COORDINATION

Since the LHC ceased operations in February, a lot has been going on at Point 5, and Run Coordination continues to monitor closely the advance of maintenance and upgrade activities.

In the last months, the Pixel detector was extracted and is now stored in the pixel lab in SX5; the beam pipe has been removed and ME1/1 removal has started. We regained access to the vactank and some work on the RBX of HB has started. Since mid-June, electricity and cooling are back in S1 and S2, allowing us to turn equipment back on, at least during the day. 24/7 shifts are not foreseen in the next weeks, and safety tours are mandatory to keep equipment on overnight, but re-commissioning activities are slowly being resumed.

Given the (slight) delays accumulated in LS1, it was decided to merge the two global runs initially foreseen into a single exercise during the week of 4 November 2013. The aim of the global run is to check that we can run (parts of) CMS after several months switched off, with the new VME PCs installed, the Tracker at low temperature, one DT wheel with completed sector collector relocation, some ME11 chambers installed, HCAL new hardware, and a new YE4 disk in place. Clearly, that first global run will be a major milestone for CMS in LS1, even if we do not aim for a cosmic data taking for alignment and calibration (that will take place in 2014).

Discussions are still ongoing with the LHC and all experiments to define the running conditions in 2015.  ATLAS and CMS requests are very similar, aiming at 25ns operations while maintaining the commissioning at 50 ns to the bare minimum. Changes foreseen in machine operations include injection at a β* of 7 m or 5 m, colliding beams during the squeeze process, and luminosity levelling using β*. A slow but relatively steady commissioning of 25 ns would be accepted even if it yielded less integrated luminosity than in 2012. Checkpoints should happen in 2015 to discuss any possible issues that may appear on the way to 25 ns.

Discussions are also taking place to improve CMS operations after LS1. This includes the consolidation of the monitoring infrastructure and the refurbishment of the control room. An informal brainstorming session on this last point took place recently amongst operations experts from all subsystems, TC, DAQ, Trigger etc.