Between the Runs: Continuation and Innovation in the Shutdown of a Pa...

CERN's Large Hadron Collider (LHC) is planned to start its Run 3 in 2022 after a three-year Long Shutdown 2 (LS2). During LS2, two of its biggest particle detectors, ATLAS and CMS, have been undergoing Phase 1 Upgrade, the first of the two upgrades that will make them compatible with High-Luminosity LHC (HL-LHC) planned to start with operation in 2027-2028. HL-LHC will be probing new physics at unprecedented energy scales and collision rates until the end of the HL-LHC operation in 2034.

The talk first identifies and analyzes notions of maintenance employed by the physicists and engineers involved in the upgrade of a subsystem of the ATLAS detector. They can mean maintenance during everyday operation, yearly maintenance of the supporting infrastructure such as powering and cooling systems, and finally, longer shutdowns as the designated maintenance time in the lifetime of a detector, when the ATLAS 'opens' and the subdetectors it consists of can be physically accessed. These different notions of maintenance can be captured by the categories of maintenance as 'repair', 'prevention', 'devaluation', and 'revaluation', thus corresponding to different types of retrospective and prospective care practices (Schabacher 2021).

However, the shutdown upgrade periods necessarily intertwine maintenance with innovation, since the prospective direction of care doesn't exhaust in the aim of continuation, but also in designing and implementing innovative solutions whose temporalities have a fixed, planned endpoint - the end of HL-LHC operation. The talk aims to show how continuation and innovation coevolve and constrain one another in a detector upgrade. It is based on qualitative interviews with physicists and engineers involved in the upgrade of an ATLAS subdetector.