The LHC’s first long shutdown has provided the opportunity for a major programme of consolidation and improvements on the ATLAS detector. One of the biggest interventions concerns the insertion of a fourth, innermost layer for the pixel detector. This has required the so-called “big opening” of ATLAS in which one of the small muon wheels is lifted to the surface. The pixel detector itself has also been raised to the surface for repair work. Other activities include improvements to the muon chambers and calorimeters, as well as a great deal of consolidation work on infrastructure.

Read more: "ATLAS undergoes some delicate gymnastics" – CERN Courier