CERN Accelerating science

ALICE Run Manager (19 Aug - 1 Sep): Peiyu Li

• LHC:
  The LHC has provided stable beams for physics production until Monday morning when a third block of planned Machine Developments started. Last Friday the operations were interrupted for an urgent intervention to replace a cryogenic compressor in Point 6. At the same time, a fire broke out in a room in Point 4 where some electronics for the LHC compensators is located. The fire was promptly extinguished, but the machine had to operate without the Point 4 compensator over the weekend, which was considered a relatively low-risk option. Beam operations finally resumed in the late evening of Friday, and continued quite smoothly during the weekend.
  
  The Machine Development block started on Monday 19 at 7 am, and continued during the whole week. The MD schedule was severely affected by an issue with the RF system that appeared on Tuesday when some special settings for a high-intensity test were reverted. At this point, the RF did not restart properly, and this led to long investigations that were only successfully concluded on Thursday afternoon. During this time only low-intensity tests not involving bunch trains could be performed.
  
  The proton-proton physics production will resume today (Friday) afternoon after 4 pm, and will continue until the next MD block at the end of September.
   
• P2 operations:
  ALICE has collected good physics data until the beginning of the Machine Development. The total recorded luminosity for proton-proton physics production has reached close to 34 /pb before the start of the MD.
  
  On the afternoon of Monday, after the start of the MD program, we experienced a power cut of several electronics racks on the I-side of the experiment, with a significant impact on several detectors (MFT, MID, TOF, TPC and TRD). The issue was traced back to a faulty circuit breaker in the LHC service tunnel, that was replaced by the EN-EL technicians. Fortunately, all affected equipment could be completely recovered with no damage to the electronics.
  
  The week has been mainly devoted to tests of the central software since all detectors were kept nearly off during the MD fills. On Thursday we also performed the periodic upgrade of the production software. The new software included a faster version of the TPC GPU reconstruction code and several bugfixes to further improve the data-taking stability.
  
  Today (Friday) afternoon, at the end of the MD program, we will invert the polarity of the magnets to the negative configuration. We will then resume the p-p physics data taking with this configuration until the next MD block.