Programmed Stops Coordination: from Preparation to Completion

The exploitation of the CERN accelerator complex requires programmed stops of the operation, to execute various activities as standard maintenances, upgrades, consolidations and projects implementations. The Sec-ond Long Shutdown (LS2) of the LHC and its Injectors started in December 2018 and was completed by the end of 2020 for the Injectors and early 2022 for the Large Hadron Collider (LHC). A huge number of activities were performed during this period, with challenges at various levels, from technical, to organizational and managerial. This paper presents the coordination of the Programmed Stops of the CERN accelerator complex, within the Accelerator Coordination & Engineering (EN-ACE) Group for the LHC and its injectors, from the preparation process to the completion of these periods. It takes the recent LS2 as a reference, and it highlights key points of success and lessons learnt in terms of general coordination, quality assurance, configuration and lay-out management, spatial integration, planning and scheduling, operational safety, logistics and worksite coordination. It introduces the preparation of the Run 3 Programmed Stops coordination based on the successful LS2 methodology.