On 10 December 2018, LHC Run 2 came to an end, and the symbolic key to the machine was handed over to the aptly-named ACE (Accelerator Coordination and Engineering) group in the Engineering Department. Two years and one pandemic later, it is now back in the hands of the operators, and preparations are underway to bring the LHC back to life later this year.

During Long Shutdown 2 (LS2), major equipment has been installed within the framework of several projects. The LIU project, in addition to the large number of injector upgrades, was also very active in the LHC tunnel, with the implementation of a new design for the transfer lines from the SPS to the LHC. Even if most of the activities for the HL-LHC project will take place during LS3, major works were performed during LS2: the upgrade of the cryogenics system at LHC Point 4, the installation of numerous innovative collimators, civil engineering at LHC Points 1 and 5, to list only a few. As part of the DISMAC project, the electrical insulation of all 1232 LHC dipole diodes was consolidated and 22 magnets were replaced in the machine.

FASER (Forward Search Experiment) has also been installed in the LHC; it will be taking data during Run 3.

The LS2 was a fundamental milestone for allowing the LHC to reach unprecedented energy levels for the new era of high luminosity, opening the door to new discoveries, but it was also instrumental for the building of strong and trustful relationships between all stakeholders. By consolidating, upgrading, maintaining and optimising the accelerator complex, teams worked towards a more powerful and reliable discovery factory. “Long Shutdown 2 federated people around a common project,” explains Marzia Bernardini, in charge of the organisation, scheduling and support section in the EN-ACE group, “especially when circumstances require constant rescheduling. The LS2 helped us to understand each other as we listen and debate to find common solutions, putting aside our egos and working towards a common goal.”

When the LHC key was handed back to the Operations group in the Beams Department, on 15 March, it was an opportunity for the LS2 teams to celebrate a mission accomplished. “This key somehow represents the values and knowledge of the scientific community,” says Marzia, “the work of hundreds of Cernois, collaborators, contractors, fellows, project associates: everyone has contributed with passion, commitment and professionalism to the success of LS2. It was a wonderful challenge that we were able to take on together.”

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